Year:
170 questions
🧬 Organic — Nomenclature
Identifying homologous series · IUPAC naming · isomers · functional groups · general formulae
November 2016
Q5 — Organic Nomenclature
The letters A to F in the table below represent six organic compounds. H H H H H O H H C C C H
5.1 Write down the LETTER that represents the following:
5.1.1 A hydrocarbon (1)
5.1.2 A functional isomer of compound B (1)
5.1.3 A compound which belongs to the same homologous series as compound D (1)
5.2 Write down the STRUCTURAL FORMULA of EACH of the following:
5.2.1 Compound C (3)
5.2.2 The acid used to prepare compound D (2)
5.3 Compound A reacts with an unknown reactant, X, to form 2-methylpropane.
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March 2017
Q6 — Organic Nomenclature
(3) (2)
6.1 Define the term functional group of organic compounds. (2)
6.2 Write down the:
6.2.1 Structural formula of the functional group of aldehydes (1)
6.2.2 Name of the functional group of carboxylic acids (1)
6.3 The IUPAC name of an organic compound is 2,4-dimethylhexan-3-one. For this compound, write
6.3.1 Homologous series to which it belongs (1)
6.3.2 Structural formula (3)
6.4 Write down the IUPAC names of the following compounds:
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June 2017
Q7 — Organic Nomenclature
The letters A to F in the table below represent six organic compounds. H CH3 CH3 A CH3CH2CH2CHO B H C C C CH2 H CH3
7.1 Write down the letter that represents EACH of the following:
7.1.1 A hydrocarbon (1)
7.1.2 An alcohol (1)
7.1.3 An ester (1)
7.2 Write down the IUPAC name of:
7.2.1 Compound A (1)
7.2.2 Compound B (3)
7.3 Compound C is a functional isomer of compound A. Write down the structural formula of compound C.(2)
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November 2017
Q8 — Organic Nomenclature
For this compound, write down the:
8.1 Study the structural formula below. For this compound, write down the:
8.1.1 Homologous series to which it belongs (1)
8.1.2 IUPAC name (2)
8.1.3 IUPAC name of the organic acid used in its preparation (1)
8.1.4 STRUCTURAL FORMULA of its straight chain (unbranched) functional isomer (2)
8.2 Write down the structural formula of 4-methylpentan-2-one. (3)
8.3 Consider the structural formula below.
8.3.1 General formula of the homologous series to which it belongs (1)
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March 2018
Q9 — Organic Nomenclature
The letters A to E in the table below represent six organic compounds.
9.1 Write down the LETTER that represents EACH of the following:
9.1.1 A tertiary alcohol (1)
9.1.2 An aldehyde (1)
9.1.3 A ketone (1)
9.1.4 A functional isomer of compound B (1)
9.2 Write down the IUPAC name of:
9.2.1 Compound B (1)
9.2.2 Compound E (4)
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June 2019
Q10 — Organic Nomenclature
The letters A to F in the table below represent six organic compounds. compound A (3)
10.1 Is compound C SATURATED or UNSATURATED? Give a reason for the answer. (2)
10.2 Write down the LETTER that represents each of the following:
10.2.1 An ester (1)
10.2.2 A FUNCTIONAL ISOMER of butanal (1)
10.2.3 A compound with the general formula CnH2n-2 (1)
10.2.4 A compound used as reactant in the preparation of compound D (1)
10.3 Write down the STRUCTURAL FORMULA of:
10.3.1 The functional group of compound C (1)
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November 2019
Q11 — Organic Nomenclature
belongs. (1) H O H H H H C C C C C H H H H H
11.1 The IUPAC name of an organic compound is 4,4-dimethylpent-2-yne.
11.1.1 Write down the GENERAL FORMULA of the homologous series to which this compound
11.1.2 Write down the STRUCTURAL formula of this compound. (3)
11.2 The organic compound below has one positional isomer and one functional isomer.
11.2.1 Define the term positional isomer. (2)
11.2.2 IUPAC name of its POSITIONAL isomer (2)
11.2.3 Structural formula of its FUNCTIONAL isomer (2)
11.3 Consider the condensed structural formula of an organic compound below.
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November 2020
Q12 — Organic Nomenclature
The letters A to E in the table below represent five organic compounds. A B C3H8O C ...
12.1 For compound D, write down the:
12.1.1 Homologous series to which it belongs (1)
12.1.2 IUPAC name of a FUNCTIONAL ISOMER (2)
12.2 Write down the:
12.2.1 IUPAC name of compound A (3)
12.2.2 STRUCTURAL FORMULA of compound E (2)
12.3 Compound B is a primary alcohol.
12.3.1 Write down the meaning of the term primary alcohol. (2)
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June 2021
Q13 — Organic Nomenclature
The letters A to F in the table below represent six organic compounds. are formed. For the ORGANIC product formed, write down the: and an alkane Q, as shown below. C10H22 → P + Q
13.1 Write down the LETTER(S) that represent(s) the following:
13.1.1 A ketone (1)
13.1.2 TWO compounds that are FUNCTIONAL ISOMERS (1)
13.1.3 A hydrocarbon (1)
13.2 For compound D, write down the:
13.2.1 Homologous series to which it belongs (1)
13.2.2 IUPAC name (3)
13.3 Consider compound F. Write down the IUPAC name of its:
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September 2021
Q14 — Organic Nomenclature
The letters A to E in the table below represent five organic compounds. 2CxHy + 25O2(g) → 16CO2(g) + 18H2O(g) The reaction above takes place in a closed container at a constant temperature higher than...
14.1 Write down the LETTER that represents EACH of the following:
14.1.1 A ketone (1)
14.1.2 A hydrocarbon (1)
14.1.3 An alkene (1)
14.2 Write down the:
14.2.1 IUPAC name of compound A (3)
14.2.2 STRUCTURAL FORMULA of compound D (2)
14.2.3 IUPAC name of the STRAIGHT CHAIN FUNCTIONAL ISOMER of compound C (2)
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November 2021
Q15 — Organic Nomenclature
The letters A to H in the table below represent eight organic compounds.
15.1 Define the term unsaturated compound. (2)
15.2 Write down the:
15.2.1 Letter that represents an UNSATURATED compound (1)
15.2.2 NAME of the functional group of compound C (1)
15.2.3 Letter that represents a CHAIN ISOMER of compound C (2)
15.2.4 IUPAC name of compound G (3)
15.2.5 General formula of the homologous series to which compound E belongs (1)
15.3 Define the term functional isomers. (2)
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June 2022
Q16 — Organic Nomenclature
The letters A to H in the table below represent eight organic compounds.
16.1 Write down the LETTER that represents a compound that:
16.1.1 Is a ketone (1)
16.1.2 Has the general formula CnH2n-2 (1)
16.1.3 Is an isomer of 2-methylbut-2-ene (1)
16.1.4 Has the same molecular formula as ethyl ethanoate (1)
16.2 Write down the:
16.2.1 IUPAC name of compound A (3)
16.2.2 STRUCTURAL FORMULA of compound F (3)
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November 2022
Q17 — Organic Nomenclature
A to F in the table below represent six organic compounds Compound S has an EMPIRICAL FORMULA of C3H6O and a molecular mass of 116 g∙mol-1.
17.1 Write down the:
17.1.1 Letters that represent TWO organic compounds that are isomers of each other (1)
17.1.2 Type of isomers (CHAIN, FUNCTIONAL or POSITIONAL) identified in QUESTION 17.1.1 (1)
17.1.3 GENERAL FORMULA of the homologous series to which compound B belongs (1)
17.1.4 NAME of the functional group of compound F (1)
17.2 Write down the IUPAC name of:
18.2.1 Compound A (3)
18.2.2 Compound B (2)
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June 2023
Q18 — Organic Nomenclature
Study the table below and answer the questions that follow. compound A (3) compound E is 88 g∙mol-1. Determine the mol...
18.1 Define the term unsaturated hydrocarbon. (2)
18.2 Write down the:
18.2.1 Letter that represents an UNSATURATED hydrocarbon (1)
18.2.2 IUPAC name of compound A (3)
18.2.3 IUPAC name of the POSITIONAL isomer of compound B (2)
18.2.4 IUPAC name of compound D (2)
18.2.5 Balanced equation, using MOLECULAR FORMULAE, for the complete combustion of
18.3 The formula C4H8O represents two compounds that are functional isomers of each other.
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November 2023
Q19 — Organic Nomenclature
The letters A to H in the table below represent eight organic compounds.
19.1 Define the term organic compound. (1)
19.2 Write down the IUPAC name of compound:
19.2.1 E (2)
19.2.2 H (2)
19.3 Write down the:
19.3.1 STRUCTURAL formula of compound B (2)
19.3.2 STRUCTURAL formula of compound C (3)
19.3.3 General formula of the homologous series to which compound E belongs (1)
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June 2024
Q20 — Organic Nomenclature
The letters A to H in the table below represent eight organic compounds. balanced equation for this reaction. (3)
20.1 Define the term hydrocarbon. (2)
20.2 Write down the letter(s) for:
20.2.1 TWO compounds that are UNSATURATED hydrocarbons (1)
20.2.2 TWO compounds that are CHAIN ISOMERS of each other (2)
20.2.3 A secondary alcohol (1)
20.3 Write down the:
20.3.1 STRUCTURAL formula of the FUNCTIONAL ISOMER of compound D (2)
20.3.2 General formula of the homologous series to which compound B belongs (1)
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November 2024
Q21 — Organic Nomenclature
The letters A to H in the table below represent organic compounds. of a catalyst. Write down the: PHYSICAL PROPERTIES Melting point
21.1 Write down the LETTER that represents EACH of the following:
21.1.1 An alcohol (1)
21.1.2 A compound with a formyl group (1)
21.1.3 An unsaturated compound (1)
21.2 Write down the IUPAC name of compound:
21.2.1 B (3)
21.2.2 E (3)
21.3 Two different compounds in the above table are functional isomers.
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🌡️ Organic — Physical Properties
Boiling points · vapour pressure · intermolecular forces · comparing compounds
November 2014
Q1 — Physical Properties
investigations, they determine the boiling points of the first three alkanes. Explain this observation by referring to the TYPE of INTERMOLECULAR FORCES present in each of these compounds. ...
1.1 Give a reason why alkanes are saturated hydrocarbons. (1)
1.2 Write down the structural formula of:
1.2.1 The functional group of alcohols (1)
1.2.2 A tertiary alcohol that is a structural isomer of butan-1-ol (2)
1.3 Learners investigate factors that influence the boiling points of alkanes and alcohols. In one of the
1.3.1 Write down an investigative question for this investigation. (2)
1.3.2 Fully explain why the boiling point increases from methane to propane. (3)
1.4 The learners find that the boiling point of propan-1-ol is higher than that of propane.
June 2015
Q2 — Physical Properties
The table below shows five organic compounds represented by the letters A to E. B CH3CH3 C CH3CH2CH3 D CH3CH2CH2CH3
2.1 Is compound B SATURATED or UNSATURATED? Give a reason for the answer. (2)
2.2 Write down the boiling point of:
3.2.1 Compound C (1)
3.2.2 Compound E (1)
2.3 Explain the difference in boiling points of compounds C and E by referring to the TYPE of
2.4 Does vapour pressure INCREASE or DECREASE from compounds A to D? Fully explain the answer. (4)
2.5 How will the vapour pressure of 2-methylpropane compare to the vapour pressure of compound D?
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November 2015
Q3 — Physical Properties
Four compounds of comparable molecular mass are used to investigate the effect of functional groups on vapour pressure. The results obtained are shown in the table below. VAPOUR PRESSURE (kPa at 20 °C...
3.1 Define the term functional group of an organic compound. (2)
3.2 Which ONE of the compounds (A, B, C or D) in the table has the:
3.2.1 Highest boiling point
3.2.2 Weakest intermolecular forces (1)
3.3 Refer to the type of intermolecular forces to explain the difference between the vapour pressure of
3.4 The vapour pressures of compounds C and D are much lower than those of compounds A and B.
3.5 Briefly explain the difference in vapour pressure between compound C and compound D. (2)
3.6 During a combustion reaction in a closed container of adjustable volume, 8 cm 3 of compound A
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March 2016
Q4 — Physical Properties
The relationship between strength of intermolecular forces and boiling point is investigated using four organic compounds from different homologous series. The compounds and their boiling points are g...
4.1 Define the term boiling point. (2)
4.2 What is the relationship between strength of intermolecular forces and boiling point? (1)
4.3 Refer to the TYPE and the STRENGTH of intermolecular forces to explain the difference in boiling
4.3.1 Compounds A and B (3)
4.3.2 Compounds C and D (3)
4.4 Is compound B a GAS or a LIQUID at room temperature? (1)
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June 2016
Q5 — Physical Properties
The relationship between boiling point and the number of carbon atoms in straight chain molecules of alkanes, carboxylic acids and alcohols is investigated. Curves P, Q and R are obtained. GRAPH OF BO...
5.1 Define the term boiling point. (2)
5.2 For curve P, write down a conclusion that can be drawn from the above results. (2)
5.3 Identify the curve (P, Q or R) that represents each of the following:
5.3.1 Alkanes (1)
5.3.2 Carboxylic acids (1)
5.4 Explain the answer to QUESTION 5.3.2 by referring to the:
November 2016
Q6 — Physical Properties
The boiling points of three isomers are given in the table below. ISOMERS BOILING POINT (°C) A 2,2-dimethylpropane 9 B 2-methylbutane 28
6.1 Define the term structural isomer. (2)
6.2 What type of isomers (POSITIONAL, CHAIN or FUNCTIONAL) are these three compounds? (1)
6.3 Explain the trend in the boiling points from compound A to compound C. (3)
6.4 Which ONE of the three compounds (A, B or C) has the highest vapour pressure? Refer to the data
6.5 Use MOLECULAR FORMULAE and write down a balanced equation for the complete combustion
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June 2017
Q7 — Physical Properties
Learners investigate factors which influence the boiling points of alcohols. They use equal volumes of each of the alcohols and heat them separately in a water bath. The temperature at which each boil...
7.1 Define the term boiling point. (2)
7.2 What property of alcohols requires them to be heated in a water bath? (1)
7.3 The boiling points of the alcohols are compared with each other.
7.3.1 What structural requirements must the alcohols meet to make it a fair comparison? (2)
7.3.2 Fully explain the trend in the boiling points. (3)
7.4 How will the boiling point of hexan-1-ol be affected if the volume of hexan-1-ol used is doubled?
7.5 In another investigation the learners compare the boiling points of hexan-1-ol and hexanal.
7.5.1 Write down the independent variable for this comparison. (1)
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November 2017
Q8 — Physical Properties
The vapour pressure versus temperature graph below was obtained for four straight chain (unbranched) alkanes (P, Q, R and S). FROM P TO S, EACH COMPOUND DIFFERS FROM THE PREVIOUS COMPOUND BY A –CH2 GR...
8.1 Give a reason why alkanes are said to be SATURATED. (1)
8.2 Define vapour pressure. (2)
8.3 Use the information in the graph above to answer the following questions.
10.3.1 What is the effect of an increase in temperature on vapour pressure?
8.3.2 Which compound has a boiling point of approximately 68 °C? Give a reason for the answer. (2)
8.3.3 Which compound has the longest chain length? Fully explain the answer. (4)
8.4 Compound P has FIVE carbon atoms.
8.4.1 Draw the structural formula of a chain isomer of P. Write down the IUPAC name of this
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March 2018
Q9 — Physical Properties
Study the vapour pressure versus temperature graphs for three organic compounds, X, Y and Z, below which belong to different homologous series. Atmospheric pressure is 100 kPa. identified in random or...
9.1 Write down the vapour pressure of compound Y at 90 °C. (1)
9.2 The graphs can be used to determine the boiling points of the three compounds.
9.2.1 Define boiling point. (2)
9.2.2 Determine the boiling point of compound X. (1)
9.3 The homologous series to which the three compounds of similar molecular masses belong, were
9.3.1 Which compound (X, Y or Z) is the carboxylic acid? (1)
9.3.2 Explain the answer to QUESTION 9.3.1 by referring to the type of intermolecular forces in
9.3.3 Compound X has three carbon atoms per molecule. Write down its IUPAC name. (1)
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June 2018
Q10 — Physical Properties
The boiling points of straight-chain alkanes and straight-chain alcohols are compared in the table. NUMBER OF BOILING POINTS OF BOILING POINTS OF CARBON ATOMS ALKANES (°C) ...
10.1 Explain the increase in boiling points of the alkanes, as indicated in the table. (3)
10.2 Explain the difference between the boiling points of an alkane and an alcohol, each having
10.3 Does the vapour pressure of the alcohols INCREASE or DECREASE with an increase in the
10.4 How will the boiling point of 2-methylpropane compare to that of its chain isomer?
November 2018
Q11 — Physical Properties
The boiling points of different organic compounds are given below. COMPOUND BOILING POINT (°C) A HCOOH 101 B CH3COOH 118
11.1 Define boiling point. (2)
11.2 Write down the:
11.2.1 Name of the FUNCTIONAL GROUP of these compounds (1)
11.2.2 IUPAC name of compound C (1)
11.2.3 Structural formula of the FUNCTIONAL isomer of compound B (2)
11.3 Which ONE of the compounds, A or B or C, has the highest vapour pressure? Refer to the data in
11.4 The boiling point of compound B is now compared with of compound X.
11.4.1 Besides the conditions used to determine boiling points, give a reason why this is a fair
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June 2019
Q12 — Physical Properties
Three compounds are used to investigate one of the factors that influences boiling point. The results obtained are shown in the table below. MOLECULAR MASS BOILING POINT (g·mol-1) (°C...
12.1 In one investigation, the boiling points of compound B and compound C are compared.
12.1.1 Is this a fair investigation? Write down YES or NO. Refer to the data in the table and give a
12.1.2 Write down the independent variable for this investigation. (1)
12.2 Which ONE of the compounds (A, B or C) has the highest vapour pressure? Give a reason for the
12.3 Refer to the intermolecular forces present in each compound and FULLY explain the trend in boiling
12.4 Which compound, BUTAN-1-OL or PROPAN-1-OL, has the higher boiling point? Give a reason for
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November 2019
Q13 — Physical Properties
The boiling points of five organic compounds (P, Q, R, S and T) are studied. COMPOUND IUPAC NAME P Pentanal Q 2,2-dimethylbutane
13.1 Define the term boiling point. (2)
13.2 Give a reason why this is a fair comparison. (1)
13.3 Which ONE of the three boiling points is most likely the boiling point of compound R? Explain the
13.4 A mixture of equal amounts of P and T is placed in a flask and heated to a temperature below their
13.4.1 Which compound (P or T) will be present in a greater amount in the SYRINGE? (2)
13.4.2 Explain the answer to QUESTION 13.4.1 by referring to the TYPES and STRENGTHS of
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November 2020
Q14 — Physical Properties
The relationship between boiling point and the number of carbon atoms in straight chain molecules of aldehydes, alkanes and primary alcohols is investigated. Curves A, B and C are
14.1 Define the term boiling point. (2)
14.2 Write down the STRUCTURAL
14.3 The graph shows that the boiling
14.4 Identify the curve (A, B or C) that
14.4.1 Compounds with London forces only (1)
14.4.2 The aldehydes and explain the answer. (4)
14.5 Use the information in the graph and write down the IUPAC name of the compound with a boiling
14.6 Write down the IUPAC name of the compound containing five carbon atoms, which has the lowest
September 2021
Q15 — Physical Properties
Compounds A, B and C are used to investigate a factor which influences the boiling points of organic compounds. The results of the investigation are given in the table below. COMPOUND ...
15.1 Is this a fair investigation? Choose from YES or NO. (1)
15.2 Give a reason for the answer to QUESTION 15.1. (1)
15.3 Fully explain the difference in the boiling points of compounds B and C. (3)
15.4 Define the term positional isomer. (2)
15.5 From compounds A, B and C, choose the letter(s) that represent(s) EACH of the following:
15.5.1 Positional isomers (1)
15.5.2 A tertiary alcohol
15.6 The graph represents the relationship between vapour pressure and temperature for compound A
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November 2021
Q16 — Physical Properties
The melting points and boiling points of four straight-chain ALKANES are shown in the table below. MELTING POINT BOILING POINT (°C) (°C) Pentane -130 ...
16.1 Define the term melting point. (2)
16.2 Write down the general conclusion that can be made about the melting points of straight chain
16.3 Name the type of Van der Waals forces between molecules of octane. (1)
16.4 Write down the predominant phase of the following alkanes at -100 °C.
16.4.1 Pentane (1)
16.4.2 Octane (1)
16.5 Hexane is now compared to 2,2-dimethylbutane.
16.5.1 Is the molecular mass of hexane GREATER THAN, LESS THAN or EQUAL to that of
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June 2022
Q17 — Physical Properties
Learners investigate factors that influence the boiling points of organic compounds. The boiling points of some organic compounds obtained are shown in the table below. MOLECULAR MASS BO...
17.1 Define the term boiling point. (2)
17.2 The boiling points of compounds A, B and C are compared.
17.2.1 How do the boiling points vary from compound A to compound C?
17.2.2 Explain the answer to QUESTION 17.2.1. (3)
17.3 The boiling points of compounds B, C and D are compared.
17.4 The boiling points of compounds E and F are compared.
17.4.1 State the independent variable for this comparison. (1)
17.4.2 Write down the name of the strongest Van der Waals force present in compound F. (1)
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November 2022
Q18 — Physical Properties
COMPOUND IUPAC NAME MELTING POINTS (°C) A Propanone ̶ 95,4 B Butanone ̶ 86,9 C Pentan-2-one ...
18.1 The melting points of some organic compounds are given in the table below.
18.1.1 To which homologous series do the above compounds belong? (1)
18.1.2 Write down the controlled variable for this comparison. (1)
18.1.3 Fully explain the difference in the melting points of these two compounds. (4)
18.2 The table below shows the results obtained from an experiment to determine the vapour pressure of
18.2.1 Define the term vapour pressure. (2)
18.2.2 Write down a suitable conclusion for this investigation. (2)
18.2.3 Write down the IUPAC name of the alcohol with the HIGHEST boiling point. (3)
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June 2023
Q19 — Physical Properties
Learners investigate the boiling points of the four organic compounds given below. ORGANIC COMPOUND MOLECULAR MASS (g·mol-1) Butanone 72 Butan-1-ol ...
19.1 Define the term boiling point. (2)
19.2 Which compound, butan-1-ol or 2-methylpropan-1-ol, will have the higher boiling point? Fully explain
19.3 Which physical property is represented by temperature X? (1)
19.4 Which curve (P, Q, R or S) represents:
19.4.1 Butanone (1)
19.4.2 Propanoic acid (1)
19.4.3 2-methylpropan-1-ol (1)
19.5 Give a reason for the answer to QUESTION 19.4.2. (1)
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November 2023
Q20 — Physical Properties
The relationship between boiling point and the molecular mass of aldehydes, carboxylic acids and primary alcohols is investigated. Curves P, R and S are obtained. All compounds used are straight chain...
20.1 Define the term boiling point. (2)
20.2 Write down the conclusion that can be made for curve P. (2)
20.3 Explain the answer to QUESTION 20.2 in terms of the structures of the compounds. (2)
20.4 Curve R represents the alcohols.
20.4.1 Which homologous series is represented by curve S? (1)
20.4.2 Explain the answer to QUESTION 20.4.1 by referring to the strength of intermolecular
20.5 For curve R, write down the:
20.5.1 Molecular mass of the compound with a boiling point of 97 °C (1)
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June 2024
Q21 — Physical Properties
The boiling points of some organic compounds are shown in the table below. The atmospheric pressure is ORGANIC COMPOUND BOILING POINT (°C) A CH3CH2CH2CH2Cℓ 78 B ...
21.1 Define the term boiling point. (2)
21.2 Which ONE of compounds A, B or C is mainly in the liquid phase at 100 °C? (1)
21.3 Explain the difference in the boiling points of compounds A and B. (3)
21.4 Consider the boiling points below.
21.4.1 Which ONE of these values represents X, the boiling point of compound D? (1)
21.4.2 Fully explain the answer to QUESTION 21.4.1. (2)
21.5 The atmospheric pressure is now changed to 83 kPa.
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2024
Q22 — Physical Properties
The vapour pressures of different organic compounds are determined at 20 °C. The vapour pressures of compounds A, B and C are NOT shown in the table. MOLAR MASS VAPOUR PRESSURE (kPa) COMPOUND ...
22.1 Define the term vapour pressure. (2)
22.2 The vapour pressures of compounds A, B and C are given in random order below.
22.2.1 Write down the vapour pressure of compound C. (1)
22.2.2 Fully explain your answer to QUESTION 22.2.1. (3)
22.3 Compounds D and E are compared.
22.3.1 Which compound has the lower boiling point? (1)
22.3.2 Fully explain the difference in the vapour pressures between compounds D and E. (4)
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⚗️ Organic — Reactions
Addition · substitution · elimination · esterification · cracking · reaction conditions
November 2014
Q1 — Organic Reactions
The flow diagram below shows the preparation of an ester using prop-1-ene as a starting reagent. P, Q, R and S represent different organic reactions. P Q Prop-1-ene ...
1.1 Write down the type of reaction represented by:
1.1.1 Q (1)
1.1.2 R (1)
1.2 For reaction P write down the:
1.2.1 Type of addition reaction (1)
1.2.2 Balanced equation using structural formulae (3)
1.3 Write down the structural formula of the haloalkane formed in reaction Q. (2)
1.4 In reaction S propan-1-ol reacts with ethanoic acid to form the ester. For this reaction write down the:
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June 2015
Q2 — Organic Reactions
Consider the incomplete equations of two reactions below. X represents the organic product formed in reaction 1, which is a SUBSTITUTION REACTION. In reaction 2, X reacts with reactant Y as shown. str...
2.1 Consider reaction 1. Write down the:
2.1.1 Type of substitution reaction that takes place (1)
2.1.2 TWO reaction conditions (2)
2.1.3 IUPAC name of compound X (1)
2.2 Consider reaction 2. Write down the:
2.2.1 Type of reaction that takes place (1)
2.2.2 Structural formula of compound Y (2)
2.2.3 IUPAC name of the organic product (2)
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November 2015
Q3 — Organic Reactions
Alcohol + P Ethyl propanoate Use the information in the flow diagram to answer the questions that follow. Write down the: Reaction 2 takes place in the presence of ...
3.1 The flow diagram below shows two organic reactions. The letter P represents an organic compound.
3.1.1 Type of reaction of which Reaction 1 is an example (1)
3.1.2 STRUCTURAL FORMULA of the functional group of ethyl propanoate (1)
3.1.3 IUPAC name of compound P (1)
3.1.4 Type of reaction of which Reaction 2 is an example (1)
3.1.5 NAME or FORMULA of the acid catalyst (1)
3.1.6 STRUCTURAL FORMULA of the alkene (2)
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March 2016
Q4 — Organic Reactions
The flow diagram below shows different organic reactions using CH 2 = CH2 as the starting reactant. X and Z represent different organic compounds. CH2 = CH2 C2H6 Reaction ...
4.1 For Reaction 1, write down the:
4.1.1 IUPAC name of compound X (2)
4.1.2 Type of addition reaction of which this is an example (1)
4.2 During Reaction 2, compound X reacts with excess hot water. Write down the:
4.2.1 STRUCTURAL FORMULA of compound Z (2)
4.2.2 NAME or FORMULA of the INORGANIC product (1)
4.4 Reaction 3 is an addition reaction.
4.4.1 Is C2H6 a SATURATED or an UNSATURATED compound? Give a reason for the answer. (2)
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June 2016
Q5 — Organic Reactions
The flow diagram below shows how prop-1-ene can be used to prepare other organic compounds. D C alcohol compound X pro...
5.1 Write down the type of reaction represented by:
5.1.1 A (1)
5.1.2 D (1)
5.1.3 F (1)
5.2 Write down the:
5.2.1 NAME or FORMULA of the catalyst needed for reaction A (1)
5.2.2 NAME or FORMULA of the inorganic reagent needed for reaction B (1)
5.2.3 Type of addition reaction represented by reaction C (1)
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November 2016
Q6 — Organic Reactions
Butane (C4H10) is produced in industry by the THERMAL cracking of long-chain hydrocarbon molecules, as shown in the equation below. X represents an organic compound that is produced. C10H22 → X + C4H1...
6.1 Write down:
6.1.1 ONE condition required for THERMAL cracking to take place (1)
6.1.2 The molecular formula of compound X (1)
6.1.3 The homologous series to which compound X belongs (1)
6.2 A mixture of the two gases, compound X and butane, is bubbled through bromine water, Br2(aq), in a
6.3 Study the flow diagram below, which represents various organic reactions, and answer the
6.3.1 IUPAC name of compound P (2)
6.3.2 Type of reaction labelled I (1)
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June 2017
Q7 — Organic Reactions
Consider the reactions represented in the flow diagram below. CH3 C CH3 concentrated Compound B reaction 3 Alcohol A (An alkene) ...
7.1 Type of reaction represented by reaction 1 (1)
7.2 NAME or FORMULA of the inorganic reactant needed for reaction 1 (1)
7.3 Type of alcohol (PRIMARY, SECONDARY or TERTIARY) of which alcohol A is an example (1)
7.4 Type of reaction represented by reaction 2 (1)
7.5 IUPAC name of compound B (2)
7.6 Type of addition reaction represented by reaction 3 (1)
7.7 Balanced equation for reaction 3 using structural formulae (4)
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November 2017
Q8 — Organic Reactions
The flow diagram below shows how an alcohol (compound P) can be used to prepare other organic compounds. The letters A to E represent different organic reactions. X, Y and Z are organic compounds.
8.1 Is compound P a PRIMARY, SECONDARY or TERTIARY alcohol? Give a reason for the answer. (2)
8.2 Write down the type of:
8.2.1 Elimination reaction represented by A (1)
8.2.2 Addition reaction represented by B (1)
8.2.3 Elimination reaction represented by D (1)
8.3 Sodium hydroxide is used as one of the reactants in reaction C.
8.3.1 What type of reaction takes place here? (1)
8.3.2 State the TWO reaction conditions for this reaction. (2)
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June 2018
Q9 — Organic Reactions
Propan-1-ol can undergo a number of organic reactions, as indicated by the letters A to D in the diagram below. for reaction A. ...
9.1 Write down the type of reaction represented by:
9.1.1 A (1)
9.1.2 B (1)
9.1.3 C (1)
9.1.4 D (1)
9.2 For reaction C, write down the:
9.2.1 Function of H2SO4 (1)
9.2.2 IUPAC name of the organic product (2)
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November 2018
Q10 — Organic Reactions
A test tube containing a straight chain organic acid X, ethanol and a catalyst is heated in a water bath, as illustrated. Organic compound Y is produced according to the following equation: X + C2H5OH...
10.1 Give a reason why the test tube is heated in a water bath instead of directly over the flame. (1)
10.2 Write down the:
10.2.1 Type of reaction that takes place here (1)
10.2.2 FORMULA of the catalyst needed (1)
10.2.3 Homologous series to which compound Y belongs (1)
10.3 Determine the molecular formula of compound Y. (2)
10.4 Write down the IUPAC name of compound Y. (2)
10.5 Write down the structural formula of the organic acid X. (2)
November 2018
Q11 — Organic Reactions
Reaction III is an example of a cracking reaction. Write down the structural formula of the MAJOR PRODUCT in this reaction. (2)
11.1 Three reactions of organic compounds from the same homologous series are shown below.
11.1.1 Define a homologous series. (2)
11.1.2 Name the type of reaction represented by I. (1)
11.1.3 Write down the formula of the inorganic compound P. (1)
11.1.4 Give the structural formula of a POSITIONAL isomer of 2-bromobutane. (2)
11.1.5 Using molecular formulae, write down a balanced equation for reaction II. (3)
11.1.6 Define a cracking reaction. (2)
11.1.7 Give the structural formula of organic compound Q. (2)
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June 2019
Q12 — Organic Reactions
Propan-1-ol undergoes two different reactions, as shown in the diagram below. Write down the:
12.1 Type of reaction represented by reaction 2 (1)
12.2 Function of concentrated H2SO4 in reaction 2 (1)
12.3 IUPAC name of compound X (2)
12.4 STRUCTURAL FORMULA of compound Y (2)
12.5 Type of reaction represented by reaction 3 (1)
12.6 IUPAC name of compound Z (2)
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November 2019
Q13 — Organic Reactions
The flow diagram below shows how compound A can be used to prepare other organic compounds. The numbers I, II, III and IV represent different organic reactions. Use the information in the flow diagram...
13.1 Name the homologous series to which compound A belongs. (1)
13.2 Write down the TYPE of reaction represented by:
13.2.1 I (1)
13.2.2 III (1)
13.2.3 IV (1)
13.3 Consider reaction III.
13.3.1 TWO reaction conditions for this reaction (2)
13.3.2 IUPAC name of the primary alcohol that is formed (2)
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November 2020
Q14 — Organic Reactions
The flow diagram shows how various organic compounds can be prepared using compound P as starting
14.1 Write down the meaning of the term hydrohalogenation. (2)
14.2 Write down the STRUCTURAL FORMULA of compound Q. (2)
14.3 Reaction I is an elimination reaction. Write down the:
14.3.1 TYPE of elimination reaction (1)
14.3.2 MOLECULAR FORMULA of compound P (1)
14.4 Write down the IUPAC name of compound R. (2)
14.5 For the HYDROLYSIS REACTION, write down the:
14.5.1 Balanced equation using structural formulae (5)
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September 2021
Q15 — Organic Reactions
R, T and U represent different organic compounds. Compound T is a CARBOXYLIC ACID and compound U is a FUNCTIONAL ISOMER of pentanoic acid. Write down the NAME of the type of reaction represented by: C...
15.1 The flow diagram below shows various organic reactions using propane as starting reactant.
15.1.1 Reaction 1 (1)
15.1.2 Reaction 2 (1)
15.1.3 Write down the IUPAC name of compound R. (2)
15.1.4 NAME or FORMULA of the catalyst (1)
15.1.5 IUPAC name of compound T (2)
15.1.6 STRUCTURAL FORMULA of compound U (2)
15.2 A laboratory technician wants to prepare but-2-ene using but-1-ene as starting reagent, as shown
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November 2021
Q16 — Organic Reactions
I, II and III represent organic reactions. Give a reason for the answer. (2) SUBSTITUTION. ...
16.1 Compound P is used as a starting reactant in each of two reactions as shown in the flow diagram below.
16.1.1 Name the type of reaction represented by I. (1)
16.1.2 Is 2-methylbutan-1-ol a PRIMARY, SECONDARY or TERTIARY alcohol?
16.1.3 Write down the STRUCTURAL FORMULA of compound P. (3)
16.1.4 Name the type of reaction represented by II. (1)
16.1.5 To which homologous series does compound Q belong? (1)
16.1.6 Name the type of reaction represented by III. Choose from ADDITION, ELIMINATION or
16.1.7 Write down the IUPAC name of compound R. (2)
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June 2022
Q17 — Organic Reactions
Compounds P and Q are ORGANIC compounds, and T is an INORGANIC compound. For reaction I, write down the: For reaction II, write down: Two STRAIGHT CHAIN organic compounds, X and Z, are produced in tes...
17.1 Study the following incomplete equations for organic reactions I and II.
17.1.1 Type of reaction that takes place (1)
17.1.2 IUPAC name of compound P (2)
17.1.3 NAME or FORMULA of compound T (1)
17.1.4 TWO reaction conditions needed (2)
17.1.5 The STRUCTURAL FORMULA of compound Q (2)
17.2 The cracking of a long chain hydrocarbon, C10H22, takes place in test tube A, as shown below.
17.2.1 State the function of the Aℓ2O3(s) in test tube A. (1)
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November 2022
Q18 — Organic Reactions
The flow diagram below shows how compound A can be used as a starting reactant to prepare two different I, II and III represent three organic reactions. equation for the reaction. ...
18.1 Is compound A a PRIMARY, SECONDARY or TERTIARY haloalkane? Give a reason for the answer. (2)
18.2 Consider reaction I.
18.2.1 Besides heat, write down the other reaction condition needed. (1)
18.2.2 Write down the type of reaction that takes place. (1)
18.2.3 Using STRUCTURAL FORMULAE for the organic compounds, write down a balanced
18.3 Consider reaction II.
18.3.1 STRUCTURAL FORMULA of compound C (2)
18.3.2 NAME or FORMULA of the inorganic reagent needed (1)
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June 2023
Q19 — Organic Reactions
P, Q and R are organic compounds. Reaction 1 is an addition reaction. Write down: Consider reaction 2. For reaction 3, write down:
19.1 The flow diagram below shows different organic reactions.
19.1.1 The TYPE of addition reaction (1)
19.1.2 ONE observable change which occurs in the container during the reaction (1)
19.1.3 The STRUCTURAL FORMULA of compound Q (2)
19.1.4 Write down the IUPAC name of compound R. (2)
19.1.5 A balanced equation using STRUCTURAL FORMULAE for the organic compounds (6)
19.1.6 The IUPAC name of alcohol P (2)
19.1.7 Write down the TYPE of elimination reaction. (1)
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November 2023
Q20 — Organic Reactions
C16H34 → C6H14 + C6Hx + 2CyHz Compound C6H14 undergoes complete combustion. A and B represent organic compounds that are POSITIONAL ISOMERS. X is an inorganic product. Write down the:
20.1 Consider the cracking reaction below.
20.1.1 Define cracking. (2)
20.1.2 Write down the values represented by x, y and z in the equation above. (3)
20.1.3 Using MOLECULAR FORMULAE, write down the balanced equation for this reaction. (3)
20.2 Consider the equations for reactions I to III below.
20.2.1 Definition of positional isomers (2)
20.2.2 Type of reaction represented by reaction I (1)
20.2.3 STRUCTURAL formula of compound B (3)
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June 2024
Q21 — Organic Reactions
Write down: compound C. Reaction 2 is an ADDITION reaction. Write down: Compound B is now used in two-step reaction to prepare compound A.
21.1 In an experiment, a test tube containing methanol, propanoic acid and a catalyst is heated in a water
21.1.1 The NAME or FORMULA of the catalyst (1)
21.1.2 The type of reaction taking place (1)
21.1.3 TWO reasons why the use of a water bath is preferred in this experiment (2)
21.1.4 The balanced equation for this reaction using STRUCTURAL FORMULAE (5)
21.1.5 The IUPAC name of the organic product for this reaction (2)
21.2 Compound A, a six-carbon branched haloalkane, is used in a two-step reaction to prepare
21.2.1 The NAME or FORMULA of the inorganic reactant in reaction 2 (1)
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November 2024
Q22 — Organic Reactions
Study the flow diagram below. Reaction I is a CRACKING REACTION forming two organic compounds, W and T, as the ONLY products. the answer. ...
22.1 Define the term cracking reaction. (2)
22.2 Is the product in reaction II a PRIMARY, SECONDARY or TERTIARY haloalkane? Give a reason for
22.3 Write down the:
22.3.1 STRUCTURAL FORMULA of compound W (3)
22.3.2 MOLECULAR formula of compound U (1)
22.4 For reaction II, write down:
22.4.1 The NAME or FORMULA of the inorganic reactant (1)
22.4.2 The type of reaction (Choose from SUBSTITUTION, ADDITION or ELIMINATION.) (1)
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⚡ Reaction Rate & Energy
Collision theory · PE diagrams · Maxwell-Boltzmann · rate graphs · factors · calculations
November 2014
Q1 — Reaction Rate
Learners use the reaction between IMPURE POWDERED calcium carbonate and excess hydrochloric acid to investigate reaction rate. The balanced equation for the reaction is: CaCO3(s) + 2HCℓ(aq) → CaCℓ2(aq...
1.1 Define the term reaction rate in words. (2)
1.2 The results of experiments 1 and 3 are compared in the investigation. Write down the:
1.2.1 Independent variable (1)
1.2.2 Dependent variable (1)
1.3 Use the collision theory to explain why the reaction rate in experiment 4 will be higher than that in
1.4 Which ONE of the graphs (A, B, C or D) represents experiment 1? Fully explain the answer by
1.5 When the reaction in experiment 4 reaches completion, the volume of gas formed is 4,5 dm3.
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March 2015
Q2 — Reaction Rate
A group of learners uses the reaction of EXCESS hydrochloric acid (HCℓ) with zinc (Zn) to investigate factors which influence reaction rate. The balanced equation for the reaction is: Zn(s) + 2HCℓ(aq)...
2.1 Is the reaction between hydrochloric acid and zinc EXOTHERMIC or ENDOTHERMIC? Give a
2.2 Give a reason for the difference in reaction rate observed for Experiments 1 and 2. (1)
2.3 The learners compare the results of Experiments 1 and 3 to draw a conclusion regarding the effect
2.4 How does the rate of the reaction in Experiment 5 compare to that in Experiment 1? Write down
2.5 Calculate the rate at which the hydrochloric acid reacts in Experiment 4 in mol·s-1.
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June 2015
Q3 — Reaction Rate
A group of learners uses the reaction of clean magnesium ribbon with dilute hydrochloric acid to investigate factors that influence reaction rate. The balanced equation for the reaction is: Mg(s) + 2H...
3.1 Is the above reaction EXOTHERMIC or ENDOTHERMIC? Give a reason for the answer. (2)
3.2 In one of the experiments 5 g magnesium ribbon was added to the hydrochloric acid solution.
3.2.1 If 30 cm3 dilute hydrochloric acid solution of concentration 1,5 mol∙dm-3 is USED UP in
3.2.2 How does the rate of the reaction change between:
3.3 In another experiment they add 5 g of magnesium to 30 cm3 of dilute hydrochloric acid of
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November 2015
Q4 — Reaction Rate
Dilute acids, indicated in the table below, react with EXCESS zinc in each of the three experiments to produce hydrogen gas. The zinc is completely covered with the acid in each experiment. EXPERIMENT...
4.1 Name TWO essential apparatuses needed to determine the rate of hydrogen production. (2)
4.2.1 Reaction rate the highest (1)
4.2.2 Mass of zinc present in the flask the
4.3 In which time interval, between t1 and t2 OR
4.4 Redraw the graph for Experiment 1 in the ANSWER BOOK. On the same set of axes, sketch
4.5 The initial mass of zinc used in each experiment is 0,8 g. The balanced equation for the reaction in
4.5.1 Calculate the mass of zinc present in the flask after completion of the reaction in
4.5.2 How will the mass of zinc present in the flask after completion of the reaction in
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June 2016
Q5 — Reaction Rate
The reaction between dilute hydrochloric acid and sodium thiosulphate (Na 2S2O3) is used to investigate one of the factors that influences reaction rate. The balanced equation for the reaction is: Na2...
5.1 State TWO factors that can influence the rate of the reaction above. (2)
5.2 Write down the NAME or FORMULA of the product that causes the cross to become invisible. (1)
5.3 Give a reason why water is added to the reaction mixture in experiments B to D. (1)
5.4 Write down an investigative question for this investigation. (2)
5.5 In which experiment (A, B, C or D) is the reaction rate the highest? (1)
5.6 Use the collision theory to explain the difference in reaction rate between experiments B and D. (3)
5.7 The original Na2S2O3 solution was prepared by dissolving 62,50 g Na2S2O3 crystals in distilled water
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March 2017
Q6 — Reaction Rate
The reaction of copper(II) carbonate with excess dilute hydrochloric acid is used to investigate the rate of reaction. The balanced equation for the reaction is: CuCO3(s) + 2HCℓ(aq) → CuCℓ2(aq) + H2O(...
6.1 State TWO ways in which the rate of the reaction above can be increased. (2)
6.2 Write down the reaction time for the reaction of the pure CuCO 3 with HCℓ. (1)
6.3 Assume that all the gas formed during the two reactions escape from the flask and that the impurities
6.3.1 Average rate of the reaction of the pure sample over the first 20 s
6.3.2 Percentage purity of the impure sample
6.3.3 Maximum volume of CO2(g) produced during the reaction of the pure sample of CuCO 3 if
6.4 Sketch a graph of the volume of gas produced versus time for the reaction of the pure CuCO 3.
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June 2017
Q7 — Reaction Rate
The apparatus below is used to investigate one of the factors that affects the rate of decomposition of hydrogen peroxide, H2O2. The balanced equation for the reaction is: 2H2O2(ℓ) → 2H2O(ℓ) + O2(g) T...
7.1 For this investigation, write down the function of the:
7.1.1 Graduated syringe (1)
7.1.2 Copper(II) oxide (1)
7.2 How will you know when the reaction is completed? (1)
7.3 Write down the independent variable for this investigation. (1)
7.4 Use the collision theory to fully explain the difference in reaction rates of experiment I and II. (3)
7.5 The graphs below show changes in the potential energy during the decomposition of hydrogen
7.5.1 Is energy ABSORBED or RELEASED during this reaction? Give a reason for the answer. (2)
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November 2017
Q8 — Reaction Rate
A group of learners uses the reaction between powdered zinc and EXCESS dilute hydrochloric acid to investigate one of the factors that affects the rate of a chemical reaction. The balanced equation fo...
8.1 Define reaction rate. (2)
8.2 Write down an investigative question for this
8.3 Which curve, P or Q, represents the results of
8.4 The average rate of the production of hydrogen gas,
8.5 In a third experiment (experiment III), 200 cm3 of a 0,25 mol∙dm-3 dilute hydrochloric acid solution at
8.5.1 How will the heat of reaction of experiment II compare with that of experiment III? Choose
8.5.2 How will the activation energy of the reaction in experiment I compare with that of the
8.6 The rate of the reaction in experiment III is higher than that of experiment I.
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March 2018
Q9 — Reaction Rate
Learners use the reaction between sodium thiosulphate and hydrochloric acid to investigate one of the factors that affects reaction rate. The balanced equation for the reaction is: Na2S2O3(aq) + 2HCℓ(...
9.1 Define reaction rate. (2)
9.2 How does the concentration of the sodium thiosulphate solution used in experiment 2 compare to
9.3 Draw a graph of average reaction rate versus volume of sodium thiosulphate used on a GRAPH
9.4 Use the information in the graph to answer the following questions.
9.4.1 Determine the volume of dilute sodium thiosulphate solution that needs to react in order for
9.4.2 Write down a conclusion for this investigation. (2)
9.5 Use the collision theory to explain the effect of an increase in concentration on reaction rate. (3)
9.6 The mass of sulphur produced in experiment 1 is 1,62 g. Calculate the mass of the sodium
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November 2018
Q10 — Reaction Rate
The reaction of zinc and EXCESS dilute hydrochloric acid is used to investigate factors that affect reaction rate. The balanced equation for the reaction is: Zn(s) + 2HCℓ(aq) ⟶ ZnCℓ2(aq) + H2(g) The r...
10.1 Experiment 1 and experiment 5 are compared. Write down the independent variable. (1)
10.2 Define reaction rate. (2)
10.3 Write down the value of x in experiment 4. (2)
10.4 The Maxwell-Boltzmann energy distribution curves for particles in each of experiments 1,
10.4.1 Experiment 3
10.4.2 Experiment 5
10.5 Experiment 6 is now conducted using a catalyst and the SAME reaction conditions as for
13.5.1 What is the function of the catalyst in this experiment? (1)
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June 2019
Q11 — Reaction Rate
Learners use the reaction of a sodium thiosulphate solution with dilute hydrochloric acid to investigate several factors that affect the rate of a chemical reaction. The balanced equation for the reac...
11.1 Define reaction rate. (2)
11.2 INVESTIGATION I
11.2.1 Dependent variable (1)
11.2.2 Conclusion that can be drawn from the results (2)
11.3 INVESTIGATION II
11.3.1 What does line P represent? (1)
11.3.2 Which curve (A or B) was obtained at the higher temperature? (1)
11.3.3 Explain, in terms of the collision theory, how an increase in temperature influences the rate
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November 2019
Q12 — Reaction Rate
The calcium carbonate (CaCO3) in antacid tablets reacts with dilute hydrochloric acid (HCℓ) according to the following balanced equation: CaCO3(s) + 2HCℓ(aq) → CaCℓ2(aq) + CO2(g) + H2O(ℓ) ...
12.1 Is the above reaction EXOTHERMIC or ENDOTHERMIC? Give a reason for the answer. (2)
12.2 Calculate the average rate (in g∙s-1) of the above reaction.
12.3 Calculate the volume of carbon dioxide, CO2(g) that will be collected at STP. Assume that all the
12.4 Write down ONE controlled variable for this investigation. (1)
12.5 Write down a conclusion that can be made from the graph. (2)
12.6 Use the collision theory to fully explain the answer to QUESTION 12.5. (3)
12.7 Redraw the graph above in the ANSWER BOOK. On the same set of axes, sketch the curve that will
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November 2020
Q13 — Reaction Rate
The reaction of calcium carbonate (CaCO3) and EXCESS dilute hydrochloric acid (HCℓ) is used to investigate one of the factors that affects reaction rate. The balanced equation for the reaction is: CaC...
13.1 For this investigation write down the:
13.1.1 Dependent variable (1)
13.1.2 Independent variable (1)
13.2 What can be deduced from the graph regarding the RATE OF THE REACTION during the time interval:
13.2.1 20 s to 40 s (1)
13.2.2 60 s to 120 s (1)
13.3 Calculate the average rate (in cm3∙s-1) at which CO2(g) is produced in the experiment.
13.4 How will the volume of CO2(g) produced in experiment B compare to that produced in experiment A?
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June 2021
Q14 — Reaction Rate
Two experiments, I and II, are conducted to investigate one of the factors that affects the rate of the reaction of aluminium carbonate, Aℓ2(CO3)3, with EXCESS hydrochloric acid, HCℓ. The balanced equ...
14.1 Define the term rate of a reaction. (2)
14.2 Using the experimental setup above, state the measurements that must be made to determine the
14.3 Use the collision theory to explain how the average reaction rate in Experiment I differs from the
14.4 The average rate of the reaction in Experiment II during the first 2,5 minutes is 4,4 x 10-3 mol∙min-1.
14.5 Calculate the maximum volume of CO2(g) that can be prepared at 25 °C in Experiment I.
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September 2021
Q15 — Reaction Rate
P and Q are the labels of the axes. What quantity is represented by: INCREASE, DECREASE or REMAINS THE SAME. (1) HCℓ(aq), is used to investiga...
15.1 Study the Maxwell-Boltzmann distribution curve for a certain reaction below.
15.1.1 P (1)
15.1.2 Q (1)
15.2 Line R represents the minimum energy required for the reaction to take place.
15.2.1 Write down the term for the underlined phrase. (1)
15.2.2 How will the shaded area on the graph be affected when a catalyst is added? Choose from
15.3 Use the collision theory to explain how a catalyst influences the rate of reaction. (4)
15.4 The reaction between POWDERED calcium carbonate, CaCO 3(s), and EXCESS hydrochloric acid,
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November 2021
Q16 — Reaction Rate
The reaction of 15 g of an IMPURE sample of calcium carbonate, CaCO 3, with EXCESS hydrochloric acid, HCℓ, of concentration 1,0 mol∙dm-3, is used to investigate the rate of a reaction. The balanced eq...
16.1 Define the term reaction rate. (2)
16.2 Give a reason why the gradient of the graph decreases between t 2 and t3. (1)
16.3 Changes in the graph between t1 and t2 are due to temperature changes within the reaction mixture.
16.3.1 Is the reaction EXOTHERMIC or ENDOTHERMIC? (1)
16.3.2 Explain the answer by referring to the graph. (3)
16.4 The percentage purity of the sample is 82,5%. Calculate the value of X on the graph assuming that
16.5 How will the reaction rate change if 15 g of a PURE sample of CaCO3 reacts with the same
16.6 Use the collision theory to explain the answer to QUESTION 16.5. (2)
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June 2022
Q17 — Reaction Rate
Learners use the reaction of MgCO3(s) with EXCESS dilute HCℓ(aq) to investigate the relationship between temperature and the rate of a chemical reaction. The balanced equation for the reaction is: MgC...
17.1 Define the term rate of reaction. (2)
17.2 State TWO conditions that must be kept constant during this investigation. (2)
17.3 Use the collision theory to explain the relationship shown in the graph. (4)
17.4 The learners obtained the graph above using 5 g MgCO 3(s) with EXCESS HCℓ at 40 °C.
17.4.1 Time taken for the reaction to run to completion (Answer: 5,238 to 5,28 min) (6)
17.4.2 Molar gas volume at 40 °C if 1,5 dm3 CO2 is collected in a syringe
17.5 The graph below represents the Maxwell-Boltzmann distribution curve for CO2(g) at 40 °C.
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November 2022
Q18 — Reaction Rate
Three experiments, A, B and C, are carried out to investigate some of the factors that affect the rate of decomposition of hydrogen peroxide, H2O2(ℓ). The balanced equation for the reaction is: 2H2O2(...
18.1 In which experiment, A or B, is the reaction rate higher? Use the collision theory to explain the
18.2 The Maxwell-Boltzmann distribution curves, X and Y, for two of the above experiments are shown
18.3 The volume of oxygen gas, O2(g), produced in experiment B during the first 3,6 s is collected in a
18.3.1 Write down the volume of O2(g) collected in the syringe. (Answer: 560 cm3) (2)
18.3.2 Calculate the mass of water, H2O(ℓ), that was produced during the first 3,6 s. Take the molar
18.4 The graph below, NOT drawn to scale, is obtained for the mass of oxygen gas produced over a period
18.4.1 Write down the rate of production of oxygen gas for the interval 30 s to 36 s. (1)
18.4.2 Will the rate of the reaction in the interval 3 s to 9 s be GREATER THAN, SMALLER THAN
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June 2023
Q19 — Reaction Rate
Consider the following decomposition reaction that takes place in a sealed 2 dm3 container: 2N2O5(g) → 4NO2(g) + O2(g) The graph below shows how the concentrations of N 2O5(g) and NO2(g) change with t...
19.1 Refer to the graph above and give a reason why curve A represents the change in the concentration
19.2 Consider the statement below:
19.3 Calculate the:
19.3.1 Mass of NO2(g) present in the container at 400 s
19.3.2 Average rate of production of O2(g) in mol∙dm-3∙s-1 in 700 s
19.4 The Maxwell-Boltzmann distribution curve for the N2O5(g) initially present in the container is shown
19.4.1 Redraw the distribution curve above in the ANSWER BOOK and label this curve as P.
19.4.2 Will the rate of decomposition of N2O5(g) at the higher concentration be HIGHER THAN,
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November 2023
Q20 — Reaction Rate
The reaction between EXCESS dilute hydrochloric acid and sodium thiosulphate is used to investigate factors that influence reaction rate. Na2S2O3(aq) + 2HCℓ(aq) → 2NaCℓ(aq) + S(s) + H2O(ℓ) + SO2(g) Th...
20.1 Define reaction rate. (2)
20.2 Write down the independent variable for this investigation. (1)
20.3 Calculate the value of P in the table.
20.4 When 0,21 g of sulphur has formed in Run 1, the cross becomes invisible.
20.5 Sketch the Maxwell-Boltzmann distribution curve for the reaction at 20 °C.
20.6 Explain the effect of temperature on reaction rate in terms of the collision theory. (4)
June 2024
Q21 — Reaction Rate
The reaction between aluminium and EXCESS sulphuric acid is used to investigate factors affecting rates of 2Aℓ(s) + 3H2SO4(aq) → Aℓ2(SO4)3(aq) + 3H2(g) The effect of a catalyst on the rate of reaction...
21.1 INVESTIGATION I
21.1.1 Is the reaction between Aℓ(s) and dilute H2SO4(aq) ENDOTHERMIC or EXOTHERMIC?
21.1.2 What does the shaded area to the right of line P represent? (1)
21.1.3 Determine the numerical value represented by the letter X on diagram B. (Answer: 32,6 kJ) (2)
21.2 INVESTIGATION II
21.2.1 The size of the shaded area (diagram B) (1)
21.2.2 The value of Y (1)
21.2.3 The TOTAL volume of hydrogen gas produced (1)
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November 2024
Q22 — Reaction Rate
investigate the factors that affect the rate of a reaction. The balanced equation for the reaction is: 2Aℓ(s) + 6HCℓ(aq) → 2AℓCℓ 3(aq) + 3H2(g) EXPERIMENT I In this experiment, 1 mol∙dm-3 HCℓ solution...
22.1 The reaction between pure aluminium, Aℓ(s), and EXCESS hydrochloric acid, HCℓ(aq), is used to
22.1.1 Define the term reaction rate. (2)
22.1.2 For the time interval t = 0 to t = 5 minutes, the average reaction rate for the formation of
22.1.3 Use the collision theory to explain the change in the reaction rate from t = 0 to t = 5 minutes. (4)
22.1.4 Redraw the above graph (NO numerical values need to be shown) in your ANSWER BOOK
22.1.5 How will the volume of H2(g) produced in Experiment III compare to that in Experiment I?
22.2 Curve X is the Maxwell Boltzmann distribution curve for a reaction under a set of reaction conditions.
22.2.1 What change was made to obtain curve Y? (1)
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⚖️ Chemical Equilibrium
Le Chatelier · Kc calculations · ICE tables · graphs · industrial processes
November 2014
Q1 — Chemical Equilibrium
A certain amount of nitrogen dioxide gas (NO 2) is sealed in a gas syringe at 25 °C. When equilibrium is reached, the volume occupied by the reaction mixture in the gas syringe is 80 cm3. The balanced...
1.1 Define the term chemical equilibrium. (2)
1.2 At equilibrium the concentration of the NO2(g) is 0,2 mol·dm-3. The equilibrium constant for the
1.3 The diagram shows the reaction mixture in the gas syringe after equilibrium is established.
1.3.1 IMMEDIATELY after increasing the pressure, the colour of the reaction mixture in the gas
1.3.2 Use Le Chatelier's principle to explain the colour change observed in the gas syringe. (3)
1.4 The temperature of the reaction mixture in the gas syringe is now increased and a new equilibrium is
1.4.1 Colour of the reaction mixture
1.4.2 Value of the equilibrium constant (Kc)
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March 2015
Q2 — Chemical Equilibrium
Pure hydrogen iodide, sealed in a 2 dm3 container at 721 K, decomposes according to the following balanced equation: 2HI(g) ⇌ H2(g) + I2(g) ∆H = + 26 kJ∙mol-1 The graph below shows how re...
2.1 Write down the meaning of the term reversible reaction. (1)
2.2 How does the concentration of the reactant change between the 12th and the 15th minute?
2.3 The rates of both the forward and the reverse reactions suddenly change at t = 15 minutes.
2.3.1 Give a reason for the sudden change in reaction rate. (1)
2.3.2 Fully explain how you arrived at the answer to QUESTION 2.3.1. (3)
2.4 At equilibrium it is found that 0,04 mol HI(g) is present in the container. Calculate the concentration
2.5 Calculate the equilibrium constant for the reverse reaction.
2.6 The temperature is now increased to 800 K. How will the value of the equilibrium constant (K c) for the
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June 2015
Q3 — Chemical Equilibrium
Initially excess NH4HS(s) is placed in a 5 dm3 container at 218 °C. The container is sealed and the reaction is allowed to reach equilibrium according to the following balanced equation: NH4HS(s) ⇌ NH...
3.1 State Le Chatelier's principle. (2)
3.2 What effect will each of the following changes have on the amount of NH 3(g) at equilibrium?
3.2.1 More NH4HS(s) is added (1)
3.2.2 The temperature is increased (1)
3.3 The equilibrium constant for this reaction at 218 °C is 1,2 x 10 -4. Calculate the minimum mass of
3.4 How will this change affect the number of moles of H2S(g) produced? Fully explain the answer. (3)
November 2015
Q4 — Chemical Equilibrium
An unknown gas, X2(g), is sealed in a container and allowed to form X3(g) at 300 °C. The reaction reaches equilibrium according to the following balanced equation: 3X2(g) ⇌ 2X3(g) Write down only HIGH...
4.1 How will the rate of formation of X3(g) compare to the rate of formation of X2(g) at equilibrium?
4.2 Calculate the equilibrium constant, Kc, for this reaction at 300 °C. (Answer: 236,46) (4)
4.3 More X3(g) is now added to the container.
4.3.1 How will this change affect the amount of X2(g)? Write down INCREASES, DECREASES
4.3.2 Use Le Chatelier's principle to explain the answer to QUESTION 4.3.1. (2)
4.4 How does the rate of the forward reaction compare to that of the reverse reaction at t1?
4.5 Is the forward reaction EXOTHERMIC or ENDOTHERMIC? Fully explain how you arrived at the
4.6 Redraw this curve in the ANSWER BOOK. On the same set of axes, sketch the curve that will be
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June 2016
Q5 — Chemical Equilibrium
Carbon dioxide reacts with carbon in a closed system to produce carbon monoxide, CO(g), according to the following balanced equation: CO2(g) + C(s) ⇌ 2CO(g) ΔH > 0 the answer. ...
5.1 What does the double arrow indicate in the equation above? (1)
5.2 Is the above reaction an EXOTHERMIC reaction or an ENDOTHERMIC reaction? Give a reason for
5.3 How will the equilibrium concentration of the product compare to that of the reactants? Choose from
5.4 Calculate the initial amount (in moles) of CO2(g) present.
5.5 State how EACH of the following will affect the yield of CO(g) at equilibrium. Choose from
5.5.1 More carbon is added at constant temperature. (1)
5.5.2 The pressure is increased. (1)
5.5.3 The temperature is increased. (1)
November 2016
Q6 — Chemical Equilibrium
Hydrogen gas, H2(g), reacts with sulphur powder, S(s), according to the following balanced equation: H2(g) + S(s) ⇌ H2S(g) ∆H < 0 The system reaches equilibrium at 90 °C. Choose from INCREASE...
6.1 Define the term chemical equilibrium. (2)
6.2 How will EACH of the following changes affect the number of moles of H2S(g) at equilibrium?
6.2.1 The addition of more sulphur (1)
6.2.2 An increase in temperature
6.3 The sketch graph alongside was obtained for the
6.4 Calculate the equilibrium constant Kc for the reaction H2(g) + S(s) ⇌ H2S(g) at 90 °C.
March 2017
Q7 — Chemical Equilibrium
The sketch graph shows the relationship between the value of the equilibrium constant (Kc) for this reaction and temperature. How will EACH of the following changes affect the amount of NO(g) at equil...
7.1 Consider the balanced equation for a reversible reaction: N2(g) + O2(g) ⇌ 2NO(g)
7.1.1 What is meant by the term reversible reaction? (1)
7.1.2 Is the reaction ENDOTHERMIC or EXOTHERMIC? (1)
7.1.3 Fully explain the answer to QUESTION 7.1.2. (3)
7.1.4 More N2(g) is added. (1)
7.1.5 The pressure is increased by decreasing the volume. (1)
7.2 Initially 336 g titanium (Ti) and 426 g chlorine gas (Cℓ 2) are mixed in a sealed 2 dm3 container at a
7.2.1 Calculate the equilibrium constant (Kc) for the reaction at this temperature.
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June 2017
Q8 — Chemical Equilibrium
Hydrogen and iodine are sealed in a 2 dm3 container. The reaction is allowed to reach equilibrium at 700 K according to the following balanced equation: H2(g) + I2(g) ⇌ 2HI(g) Calculate the initial ma...
8.1 Give a reason why changes in pressure will have no effect on the equilibrium position. (1)
8.2 At equilibrium, 0,028 mol H2(g) and 0,017 mol I2(g) are present in the container.
8.3 What do the parallel lines in the first two minutes indicate? (1)
8.4 State TWO possible changes that could be made to the reaction conditions at t = 2 minutes. (2)
8.5 The temperature of the equilibrium mixture was changed at t = 4 minutes.
8.5.1 Is the forward reaction EXOTHERMIC or ENDOTHERMIC? Fully explain the answer. (3)
8.5.2 How will this change influence the Kc value? Choose from INCREASES, DECREASES or
8.6 What change was made to the equilibrium mixture at t = 8 minutes? (1)
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November 2017
Q9 — Chemical Equilibrium
Carbonyl bromide, COBr2, decomposes into carbon monoxide and bromine according to the following balanced equation: COBr2(g) ⇌ CO(g) + Br2(g) ΔH > 0 Initially COBr2(g) is sealed in a 2 dm3 containe...
9.1 Define chemical equilibrium. (2)
9.2 Calculate the equilibrium concentration of the COBr2(g).
9.3 Calculate the percentage of COBr2(g) that decomposed at 73 °C.
9.4 Which ONE of the following CORRECTLY describes the Kc value when equilibrium is reached at a
9.5 The pressure of the system is now decreased by increasing the volume of the container at 73 °C
March 2018
Q10 — Chemical Equilibrium
temperatures and pressures. The graph shows the percentage yield for this reaction at 30 kPa as the temperature is increased. Use the information in the graph above to answer the following to explain ...
10.1 A reversible gaseous reaction is allowed to reach equilibrium in a closed container at different
10.1.1 State Le Chatelier's principle. (2)
10.1.2 The heat of reaction (ΔH) for the forward reaction is POSITIVE. Use Le Chatelier's principle
10.1.3 Explain the effect of an increase in pressure on the equilibrium
10.1.4 Which ONE of the following equations (I, II or III) represents the
10.2 A mixture of 0,2 moles of hydrogen chloride (HCℓ) and 0,11 moles of oxygen gas (O 2) is sealed in a
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June 2018
Q11 — Chemical Equilibrium
The equation below represents a hypothetical reaction that reaches equilibrium in a closed container after 2 minutes at room temperature. The letters x, y and z represent the number of moles in the ba...
11.1 Define a dynamic equilibrium. (2)
11.2 Use the information in the graph and write down the value of:
11.2.1 x (1)
11.2.2 y (1)
11.2.2 z (1)
11.3 Calculate the equilibrium constant, Kc, for this hypothetical reaction at room temperature if the volume
11.4 At t = 4 minutes, the temperature of the system was increased to 60 °C. Is the REVERSE reaction
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November 2018
Q12 — Chemical Equilibrium
Dinitrogen tetraoxide, N2O4(g), decomposes to nitrogen dioxide, NO2(g), in a sealed syringe of volume 2 dm3. The mixture reaches equilibrium at 325 °C according to the following balanced equation: N2O...
12.1 State Le Chatelier’s principle. (2)
12.2 The syringe is now dipped into a beaker of ice water. After a while the brown colour disappears.
12.3 The volume of the syringe is now decreased while the temperature is kept constant. How will EACH
12.3.1 The number of moles of N2O4(g) (1)
12.3.2 The value of the equilibrium constant (1)
12.3.2 The rate of the forward and reverse reactions (1)
12.4 Initially X moles of N2O4(g) were placed in the syringe of volume 2 dm3. When equilibrium was
June 2019
Q13 — Chemical Equilibrium
The balanced equation below represents the reaction used in the Haber process to produce ammonia. N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH < 0 In industry the product is removed as quickly as it forms. The graph b...
13.1 Write down the meaning of the double arrow used in the equation above. (1)
13.2 Give ONE reason why ammonia is removed from the reaction vessel as quickly as it forms. (1)
13.3 Write down the percentage yield of ammonia at a temperature of 450 °C and a pressure of
13.4 Refer to Le Chatelier's principle to explain EACH of the following deductions made from the graph:
13.4.1 For a given pressure, the yield of ammonia at 500 °C is much lower than that at 350 °C (3)
13.4.2 For a given temperature, the yield of ammonia at 350 atmospheres is much higher than that
13.5 A technician prepares NH3(g) by reacting 6 moles of H2(g) and 6 moles of N2(g).
13.5.1 Calculate the maximum number of moles of NH3(g) that can be obtained in this reaction. (2)
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November 2020
Q14 — Chemical Equilibrium
The dissociation of iodine molecules to iodine atoms ( I) is a reversible reaction taking place in a sealed container at 727°C. The balanced equation for the reaction is: I 2(g) ⇌ 2I(g) Kc for the rea...
14.1 Write down the meaning of the term reversible reaction. (1)
14.2 At equilibrium the pressure of the system is increased by decreasing the volume of the container at
14.2.1 The value of the equilibrium constant (1)
14.2.2 The number of I 2 molecules (1)
14.3 Explain the answer to QUESTION 14.2.2 by referring to Le Chatelier's principle. (2)
14.4 At 227°C, the KC value for the reaction above is 5,6 x 10-12. Is the forward reaction ENDOTHERMIC
14.5 A certain mass of iodine molecules (I 2) is sealed in a 12,3 dm3 flask at a temperature of 727°C
June 2021
Q15 — Chemical Equilibrium
Pure hydrogen iodide gas, HI(g), of concentration 1 mol∙dm-3, is sealed in a 500 cm3 container at temperature T. The reaction reaches equilibrium according to the following balanced equation: 2HI(g) ⇌...
15.1 Define the term chemical equilibrium. (2)
15.2 The graph below shows how the concentrations of the reactant and products vary with time
15.2.1 Which ONE of the curves, X or Y, represents
15.2.2 How does the rate of the forward reaction
15.3 The equilibrium constant, Kc, for the reaction is 0,04 at temperature T. Calculate the number of
15.4 The graph below shows how the rates of the forward and reverse reactions change with time.
15.4.1 Which reaction(s) show(s) an increase in rate at t = 10 minutes? Choose from FORWARD,
15.4.2 Is the heat of reaction (∆H) for this reaction POSITIVE or NEGATIVE? Fully explain the
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September 2021
Q16 — Chemical Equilibrium
Steam, H2O(g), reacts with hot carbon, C(s), at 1 000 °C according to the following balanced equation: 2H2O(g) + C(s) → 2H2(g) + CO2(g) Initially, 36 g of steam and a certain amount of carbon were pla...
16.1 Define the term dynamic equilibrium. (2)
16.2 Calculate the equilibrium constant, Kc, for the reaction at 1 000 °C.
16.3 The graph shows how the rates of the forward and reverse reactions change with time.
16.3.1 Give a reason why the rate of the forward reaction decreases between t0 and t1. (1)
16.3.2 What change was made to the equilibrium mixture at t3? (1)
16.3.3 Is the forward reaction EXOTHERMIC or ENDOTHERMIC? (1)
16.3.4 Refer to Le Chatelier’s principle to explain the answer to QUESTION 16.3.3. (2)
November 2021
Q17 — Chemical Equilibrium
Consider the balanced equation below for a hypothetical reaction that takes place in a sealed 2 dm3 container 2P(g) + Q2(g) ⇌ 2PQ(g) AMOUNT (mol) AT EQUILIBRIUM
17.1 Define the term chemical equilibrium. (2)
17.2 The amount of each substance present in the equilibrium mixture at 300 K is shown in the table
17.2.1 Is the heat of the reaction (∆H) POSITIVE or NEGATIVE? (1)
17.2.2 Use Le Chatelier's principle to explain the answer to QUESTION 17.2.1. (3)
17.2.3 Calculate the equilibrium constant at 350 K.
17.2.4 How will the equilibrium constant calculated in QUESTION 17.2.3 be affected when the
17.3 More Q2(g) is now added to the reaction mixture at constant temperature. How will EACH of the
17.3.1 The yield of PQ(g) (1)
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June 2022
Q18 — Chemical Equilibrium
following balanced equation: H2(g) + I2(g) ⇌ 2HI(g) ΔH < 0 The graph below shows the concentrations of H2(g) and HI(g) versus time during the reaction. COOLED? ...
18.1 Initially, 4 moles H2(g) and 4 moles I2(g) are allowed to react in a sealed 2 dm3 flask according to the
18.1.1 Write down the value of Y. (1)
18.1.2 State Le Chatelier's principle. (2)
18.1.3 Changes were made to the temperature of the flask at time t2. Was the flask HEATED or
18.1.4 Fully explain the answer to QUESTION 18.1.3. (3)
18.2 The equation below represents the reversible reaction that takes place when NO2(g) is converted to
18.2.1 Write down the meaning of the term reversible reaction. (1)
18.2.2 Show that the equilibrium constant for this reaction is given by 2. (5)
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June 2023
Q19 — Chemical Equilibrium
One mole of pure hydrogen iodide gas, HI(g), is sealed in a 1 dm3 container at 721 K. Equilibrium is reached according to the following balanced equation: 2HI(g) ⇌ H2(g) + I2(g) It is found that 0,11 ...
19.1 State Le Chatelier's principle. (2)
19.2 Determine the number of moles of EACH of the following at equilibrium:
19.2.1 H2(g) (1)
19.2.2 HI(g) (1)
19.3 The equilibrium constant, Kc, at 721 K is 0,02.
19.3.1 Is the forward reaction EXOTHERMIC or ENDOTHERMIC? (1)
19.3.2 Fully explain the answer to QUESTION 19.3.1. (3)
19.3.3 Calculate the mass of HI(g) present at the new equilibrium at 850 K. (8)
November 2023
Q20 — Chemical Equilibrium
Consider the following hypothetical reaction reaching equilibrium in a 4 dm 3 closed container at 150 °C. 2AB(g) ⇌ A2(g) + B2(g) The graph below shows the changes in the amounts of reactants and produ...
20.2 State Le Chatelier's principle. (2)
20.3 A change was made to the equilibrium mixture at t = 80 s.
20.3.1 Write down the change made at t = 80 s. (1)
20.3.2 Use Le Chatelier's principle to explain how the system reacts to this change. (2)
20.4 Calculate the equilibrium constant, Kc, at t = 120 s. (4)
20.5 At t = 130 s the temperature of the system is decreased to 100 °C.
20.5.1 Draw a potential energy diagram for this reaction. (3)
20.5.2 Will the equilibrium constant, Kc, at 100 °C be GREATER THAN, LESS THAN or EQUAL TO
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June 2024
Q21 — Chemical Equilibrium
Consider the balanced equation for a hypothetical reaction that takes place in 2 dm 3 sealed containers. P2Q(g) + 3Q(s) ⇌ 2PQ2(g) The graphs below, not drawn to scale, are obtained for the same reacti...
21.1 State Le Chatelier's principle. (2)
21.2 What do the parallel lines after t = 5 minutes in graph A represent? (1)
21.3 Is the forward reaction EXOTHERMIC or ENDOTHERMIC? (1)
21.4 Explain the answer to QUESTION 21.3. (2)
21.5 How does the value of the equilibrium constant, Kc, for the reaction in graph B compare to that in
21.6 The equilibrium constant, Kc, is 0,49 at 398 K (graph B).
21.7 Describe the change made to the equilibrium system at t = 8 minutes, as shown in graph B, at a
21.8 Explain by using Le Chatelier's principle how the system reacts to the change in QUESTION 21.7. (2)
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November 2024
Q22 — Chemical Equilibrium
reaches equilibrium in a closed container at constant temperature T °C, according to the balanced 2CO(g) + O2(g) ⇌ 2CO2(g) ΔH < 0 Changes to the conditions of equilibrium are made at different times. ...
22.1 The reaction of carbon monoxide gas, CO(g), with oxygen gas, O 2(g), is investigated. The reaction
22.1.1 Define the term chemical equilibrium. (2)
22.1.2 At t1, oxygen, O2(g), was added to the container. Write down the letter that represents
22.1.3 At t2, the pressure is adjusted by changing the volume of the container. Was the pressure
22.1.4 Give a reason for the answer to QUESTION 22.1.3. (1)
22.1.5 Write down the NAME or FORMULA of the gas that is represented by the letter Z. (1)
22.1.6 Give a reason for the answer to QUESTION 22.1.5. (1)
22.1.7 What change in temperature is made at t3? Choose between INCREASED or DECREASED. (1)
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🧪 Acids & Bases
pH · Ka · Kw · titration · hydrolysis · conjugate pairs · indicators · buffers
November 2014
Q1 — Acids & Bases
(Answer: 0,52) (3) 4,5 g sample of the magnesium oxide in 100 cm3 hydrochloric acid of concentration 2 mol∙dm-3. (Ans...
1.1 Nitric acid (HNO3), an important acid used in industry, is a strong acid.
1.1.1 Give a reason why nitric acid is classified as a strong acid. (1)
1.1.2 Write down the NAME or FORMULA of the conjugate base of nitric acid. (1)
1.1.3 Calculate the pH of a 0,3 mol∙dm-3 nitric acid solution.
1.2 A laboratory technician wants to determine the percentage purity of magnesium oxide. He dissolves a
1.2.1 Calculate the number of moles of hydrochloric acid added to the magnesium oxide.
1.2.2 Write down the name of apparatus Q in the diagram. (1)
1.2.3 The following indicators are available for the titration:
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March 2015
Q2 — Acids & Bases
the following balanced equation: HCO-3 (aq) + H2O(ℓ) ⇌ H2CO3(aq) + OH−(aq) of HCO-3 (aq). (1) laboratory bench. Her t...
2.1 Sulphuric acid is a diprotic acid.
2.1.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
2.1.2 Give a reason why sulphuric acid is referred to as a diprotic acid. (1)
2.2 The hydrogen carbonate ion can act as both an acid and a base. It reacts with water according to
2.2.1 Write down ONE word for the underlined phrase. (1)
2.2.2 HCO-3 (aq) acts as base in the above reaction. Write down the formula of the conjugate acid
2.3 A learner accidentally spills some sulphuric acid of concentration 6 mol∙dm-3 from a flask on the
2.3.1 Calculate the volume of sulphuric acid that spilled. Assume that all the sodium hydrogen
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June 2015
Q3 — Acids & Bases
Anhydrous oxalic acid is an example of an acid that can donate two protons and thus ionises in two steps as represented by the equations below: I: (COOH)2(aq) + H2O(ℓ) ⇌ H3O+(aq) + H(COO)-2 (aq) ...
3.1 Write down:
3.1.1 ONE word for the underlined phrase in the above sentence (1)
3.1.2 The FORMULA of each of the TWO bases in reaction II (2)
3.1.3 The FORMULA of the substance that acts as ampholyte in reactions I and II. Give a reason
3.2 Give a reason why oxalic acid is a weak acid. (1)
3.3 A standard solution of (COOH)2 of concentration 0,20 mol∙dm-3 is prepared by dissolving a certain
3.4 During a titration 25 cm3 of the standard solution of (COOH)2 prepared in QUESTION 3.3 is
3.4.1 Use the burette readings and calculate the concentration of the sodium hydroxide solution.
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March 2016
Q4 — Acids & Bases
when it dissolves in water. in the solution. (Answer: 2,51 x 10-11 mol·dm-3) (5) indicator. At the endpoint it is found that 25 cm3 o...
4.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
4.2 Carbonated water is an aqueous solution of carbonic acid, H 2CO3. H2CO3(aq) ionises in two steps
4.2.1 Write down the FORMULA of the conjugate base of H2CO3(aq). (1)
4.2.2 Write down a balanced equation for the first step in the ionisation of carbonic acid. (3)
4.2.3 The pH of a carbonic acid solution at 25 °C is 3,4. Calculate the hydroxide ion concentration
4.3 X is a monoprotic acid.
4.3.1 State the meaning of the term monoprotic. (1)
4.3.2 A sample of acid X is titrated with a standard sodium hydroxide solution using a suitable
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June 2016
Q5 — Acids & Bases
HCO-3 (aq) + H2O(ℓ) ⇌ H2CO3(aq) + OH− (aq) solution of concentration 0,25 mol∙dm-3. The balanced equation for the reaction is: NaHCO3(aq) + HCℓ(aq) → NaCℓ(aq) + CO2(g) + H2O(ℓ) (Answer: 0,12 mol∙dm-3)...
5.1 Hydrogen carbonate ions react with water according to the following balanced equation:
5.1.1 Define an acid according to the Lowry-Brønsted theory. (2)
5.1.2 Write down the FORMULAE of the two acids in the equation above. (2)
5.1.3 Write down the formula of a substance in the reaction above that can act as an ampholyte. (1)
5.2 During an experiment 0,50 dm3 of a 0,10 mol∙dm-3 HCℓ solution is added to 0,80 dm3 of a NaHCO3
5.2.1 Calculate the concentration of the hydroxide ions in the solution on completion of the reaction.
5.2.2 Calculate the pH of the solution on completion of the reaction.
November 2016
Q6 — Acids & Bases
Write a relevant equation to support your answer. (3) (Answer: 0,08 mol) (2) Sodium hyd...
6.1 A learner dissolves ammonium chloride (NH4Cℓ) crystals in water and measures the pH of the solution.
6.1.1 Define the term hydrolysis of a salt. (2)
6.1.2 Will the pH of the solution be GREATER THAN, SMALLER THAN or EQUAL TO 7?
6.2 A sulphuric acid solution is prepared by dissolving 7,35 g of H2SO4(ℓ) in 500 cm3 of water.
6.2.1 Calculate the number of moles of H2SO4 present in this solution.
6.2.2 Calculate the mass of NaOH added to the H2SO4 solution. Assume that the volume of the
March 2017
Q7 — Acids & Bases
balanced equation: CH3COOH(aq) + H2O(ℓ) → CH3COO─(aq) + H3O+(aq) hydronium ions, H3O+(aq) in the solution. (Answer: 1 x 10-4 mol∙dm-3) ...
7.1 Ethanoic acid (CH3COOH) is an acid that ionises incompletely in water according to the following
7.1.1 Write down the term used for the underlined phrase above. (1)
7.1.2 An ethanoic acid solution has a pH of 4 at 25°C. Calculate the concentration of the
7.2 A standard solution of potassium hydroxide (KOH) is prepared in a 250 cm3 volumetric flask. During
7.2.1 Define a base according to the Arrhenius theory. (2)
7.2.2 Calculate the mass of potassium hydroxide used to prepare the solution above in the
7.2.3 Will the pH of the solution in the conical flask at the end point be GREATER THAN 7,
7.2.4 Explain the answer to QUESTION 7.2.3 with the aid of a balanced chemical equation. (3)
June 2017
Q8 — Acids & Bases
The Ka values for two weak acids, oxalic acid and carbonic acid, are as follows: NAME FORMULA Ka Oxalic acid (COOH)2 5,6 x 10-2 Carbonic acid ...
8.1 Define the term weak acid. (2)
8.2 Which acid, OXALIC ACID or CARBONIC ACID, is stronger? Give a reason for the answer. (2)
8.3 Oxalic acid ionises in water according to the following balanced equation:
8.4 Learners prepare 2 dm3 of a sodium hydroxide solution of concentration 0,1 mol∙dm-3. Calculate
8.5 During a titration of the sodium hydroxide solution in QUESTION 8.4 with dilute oxalic acid, the
8.5.1 Calculate the concentration of the oxalic acid solution.
8.5.2 Which ONE of the indicators above is most suitable for this titration? Give a reason for the
March 2018
Q9 — Acids & Bases
water: H2SO4(ℓ) + H2O(ℓ) ⇌ H3O+(aq) + HSO− 4 (aq) in two different experiments. The balanced equation for the reaction is: H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + H2O(ℓ) Calculate the concentration of...
9.1 The balanced equation below represents the first step in the ionisation of sulphuric acid (H2SO4) in
9.1.1 Write down the FORMULAE of the TWO bases in the equation above. (2)
9.1.2 Is sulphuric acid a STRONG or a WEAK acid? Give a reason for the answer. (2)
9.2 Learners use the reaction of a 0,15 mol∙dm-3 sulphuric acid solution with a sodium hydroxide solution
9.2.1 They use 24 cm3 of H2SO4(aq) in a titration to neutralise 26 cm 3 of NaOH(aq).
9.2.2 In another experiment, 30 cm3 of the H2SO4(aq) is added to 20 cm3 of a 0,28 mol∙dm-3 NaOH
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June 2018
Q10 — Acids & Bases
The reaction between a sulphuric acid (H2SO4) solution and a sodium hydroxide (NaOH) solution is investigated using the apparatus illustrated below. Retort stand ...
10.1 Write down the name of the experimental procedure illustrated above. (1)
10.2 What is the function of the burette? (1)
10.3 Define an acid in terms of the Arrhenius theory. (2)
10.4 Give a reason why sulphuric acid is regarded as a strong acid. (1)
10.5 Bromothymol blue is used as indicator. Write down the colour change that will take place in the
10.6 Determine the volume of H2SO4(aq) which must be added to neutralise the NaOH(aq) in the
10.7 If the learner passes the endpoint by adding 5 cm 3 of the same H2SO4(aq) in excess, calculate the
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November 2018
Q11 — Acids & Bases
I: H2SO4(ℓ) + H2O(ℓ) ⇌ H3O+(aq) + HSO− 4 (aq) II: HSO−4 (aq) + H 2O(ℓ) ⇌ H 3O +(aq) + SO2− (aq) sulphuric acid. ...
11.1 Sulphuric acid is a strong acid present in acid rain. It ionises in two steps as follows:
11.1.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
11.1.2 Write down the FORMULA of the conjugate base of H3O+(aq). (1)
11.1.3 Write down the FORMULA of the substance that acts as an ampholyte in the ionisation of
11.2 Acid rain does not cause damage to lakes that have rocks containing limestone (CaCO 3).
11.2.1 Define hydrolysis of a salt. (2)
11.2.2 Explain, with the aid of the relevant HYDROLYSIS reaction, how limestone can neutralise
11.3 The water in a certain lake has a pH of 5.
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June 2019
Q12 — Acids & Bases
0,4 g of XHCO3 in 100 cm3 of water. She then titrates all of this solution with a 0,2 mol dm-3 hydrochloric acid (HCℓ) solution. Methyl orange is used as the indicator during the titration. (Answer: p...
12.1 Define a base in terms of the Arrhenius theory. (2)
12.2 Explain how a weak base differs from a strong base. (2)
12.3 Write down the balanced equation for the hydrolysis of NaHCO 3. (3)
12.4 A learner wishes to identify element X in the hydrogen carbonate, XHCO3. To do this she dissolves
12.4.1 Calculate the pH of the hydrochloric acid solution.
12.4.2 Give a reason why methyl orange is a suitable indicator in this titration. (1)
12.4.3 Identify element X by means of a calculation.
November 2019
Q13 — Acids & Bases
A hydrogen bromide solution, HBr(aq), reacts with water according to the following balanced chemical equation: HBr(aq) + H2O(ℓ) ⇌ Br ‒(aq) + H3O+(aq) The Ka value of HBr(aq) at 25 °C is 1 x 109. Zn(OH...
13.1 Is hydrogen bromide a STRONG ACID or a WEAK ACID? Give a reason for the answer. (2)
13.2 Write down the FORMULAE of the TWO bases in the above reaction. (2)
13.3 HBr(aq) reacts with Zn(OH)2(s) according to the following balanced equation:
13.3.1 Calculate the pH of the HBr solution remaining in the flask AFTER the reaction with
13.3.2 Calculate the mass of Zn(OH)2(s) INITIALLY present in the flask if the initial concentration
November 2020
Q14 — Acids & Bases
hydronium ions, H3O+(aq), in the solution. (Answer: 1,41 x 10-4 mol∙dm-3) (3) Sodium ethanoate, CH3COONa(aq), forms when ethanoic acid reacts with sodium hydroxide. TO 7? ...
14.1 Ethanoic acid (CH3COOH) is an ingredient of household vinegar.
14.1.1 Is ethanoic acid a WEAK acid or a STRONG acid? Give a reason for the answer. (2)
14.1.2 An ethanoic acid solution has a pH of 3,85 at 25°C. Calculate the concentration of the
14.1.3 Will the pH of a sodium ethanoate solution be GREATER THAN 7, LESS THAN 7 or EQUAL
14.1.4 Explain the answer to QUESTION 14.1.3 with the aid of a balanced chemical equation. (3)
14.2 Household vinegar contains 4,52% ethanoic acid, CH3COOH by volume. A 1,2 g impure sample of
14.2.1 Calculate the number of moles of the unreacted ethanoic acid. (Answer: 0,0145 mol) (3)
14.2.2 Calcium carbonate reacts with ethanoic acid according to the following balanced equation:
September 2021
Q15 — Acids & Bases
Two beakers, A and B, contain strong bases. Beaker A: 500 cm3 of barium hydroxide, Ba(OH)2(aq) of unknown concentration X Beaker B: 400 cm3 of potassium hydroxide, KOH(aq) of concentration 0,1...
15.1 Define a base according to the Arrhenius theory. (2)
15.2 Calculate the number of moles of hydroxide ions (OH ꟷ) in beaker B. (Answer: 0,04 mol) (2)
15.3 The contents of beakers A and B are added together in beaker C. The solution in beaker C has
15.3.1 Calculate the concentration, X, of the Ba(OH)2 in beaker A.
15.3.2 Is ethanoic acid, CH3COOH(aq), a WEAK acid or a STRONG acid? Give a reason for
15.3.3 Calculate the concentration of the ethanoic acid.
November 2021
Q16 — Acids & Bases
I: H2SO4(ℓ) + H2O(ℓ) ⇌ H3O+(aq) + HSO− 4 (aq) Ka = 1 x 103 II: HSO− 2− 4 (aq) + H2O(ℓ) ⇌ H3O (aq) + SO4 (aq) + Ka = 1 x 10-2
16.1 Sulphuric acid, H2SO4, ionises into two steps as follows:
16.1.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
16.1.2 Write down the NAME or FORMULA of the substance that acts as an ampholyte in the
16.1.3 The conductivity of solutions of HSO− 4 (aq) and H2SO4(aq) are compared.
16.2 The pH of a hydrochloric acid solution, HCℓ(aq), is 1,02 at 25 °C.
16.2.1 Calculate the concentration of the HCℓ(aq). (Answer: 0,096/0,1 mol∙dm-3) (3)
16.2.2 Calculate the concentration of the EXCESS HCℓ in the new solution.
June 2022
Q17 — Acids & Bases
The pH of HX is 2,7 and the pH of HY is 0,7. HX(aq) + H2O(ℓ) ⇌ H3O+(aq) + X─(aq) The Ka value for the reaction is 1,8 x 10-5 at 25 °C. Is the concentration of the hydronium ions HIGHER THAN, LOWER THA...
17.1 Two acids, HX and HY, of EQUAL CONCENTRATIONS are compared.
17.1.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
17.1.2 Which acid, HX or HY, is STRONGER? Give a reason for the answer. (2)
17.1.3 Acid HX ionises in water according to the following equation:
17.2 Learners add 150 cm3 of a sodium hydroxide solution, NaOH, of unknown concentration to 200 cm3
17.2.1 Concentration of the H3O+ ions in the final solution
17.2.2 Initial concentration of the NaOH(aq)
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November 2022
Q18 — Acids & Bases
CH3COOH(aq) + H2O(ℓ) ⇌ CH3COO─(aq) + H3O+(aq) (Answer: 0,05 mol) (3) Ethanoic acid of volume 500 cm3 and of unknown concent...
18.1 Ethanoic acid is a weak acid that reacts with water according to the following balanced equation:
18.1.1 Define an acid in terms of the Lowry-Brønsted theory. (2)
18.1.2 Give a reason why ethanoic acid is classified as a WEAK acid. (1)
18.1.3 Write down the formulae of the TWO bases in the equation above. (2)
18.2 A flask contains 300 cm3 of dilute sodium hydroxide, NaOH(aq), of concentration 0,167 mol·dm-3.
21.2.1 Calculate the number of moles of sodium hydroxide in the flask.
18.2.2 Concentration of the OH─(aq) in the mixture
18.2.3 Initial concentration, X, of the ethanoic acid solution
June 2023
Q19 — Acids & Bases
temperature. A 0,1 mol·dm-3 H2SO4(aq) B 0,1 mol·dm-3 HNO3(aq) C 0,1 mol·dm-3 CH3COOH(aq)
19.1 The conductivity of three acid solutions, A, B and C, as shown below is investigated at the same
19.1.1 Define the term electrolyte. (2)
19.1.2 In which solution, A or B, will the bulb be brighter? Give a reason for the answer by referring
19.1.3 In which solution, B or C, will the bulb be brighter? Give a reason for the answer by referring
19.2 A hydrochloric acid solution, HCℓ(aq), is standardised by titrating it against 25 cm3 of a 0,04 mol·dm-3
19.2.1 Calculate the concentration of the HCℓ(aq).
19.2.2 Suppose a few drops of water were present in the burette before it was filled with the
19.2.3 Calculate the mass of ammonia in 1 dm3 of ChemClean.
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November 2023
Q20 — Acids & Bases
To identify metal M in an unknown metal carbonate, MCO3, the following procedure is carried out: Step 1: 0,198 g of IMPURE MCO3 is reacted with 25 cm3 of 0,4 mol∙dm-3 nitric acid, HNO3(aq). Step 2: Th...
20.1 Define the term strong base. (2)
20.2 Calculate the:
20.2.1 Number of moles of Ba(OH)2(aq) that reacted with the excess HNO3(aq)
20.2.2 pH of the solution after Step 1
20.3 The percentage purity of the MCO3(s) in the sample is 85%. Identify metal M.
June 2024
Q21 — Acids & Bases
The sodium carbonate solution is titrated with dilute hydrochloric acid, HCℓ(aq). The following indicators are available for this titration. INDICATOR pH-RANGE P 3,4 – 4,5
21.1 A standard solution is prepared by dissolving 10 g of sodium carbonate, Na 2CO3(s), in 0,7 dm3 of
21.1.1 Calculate the concentration of the solution. (Answer: 0,13 mol∙dm-3) (3)
21.1.2 Will the pH of the solution be GREATER THAN or LESS THAN 7? (1)
21.1.3 Write an equation that explains the answer to QUESTION 21.1.2. (2)
21.1.4 Which ONE of the indicators (P, Q or R) is most suitable for this titration? Give a reason for
21.2 When 0,01 moles of dilute sulphuric acid, H2SO4(aq), is mixed with 0,024 moles of potassium
21.2.1 What is meant by a dilute acid? (2)
21.2.2 Calculate the pH of the final solution. (Answer: 12,3) (8)
November 2024
Q22 — Acids & Bases
Hydrated potassium carbonate, K2CO3·xH2O, is a WEAK BASE. A solution is prepared by dissolving some of this solid in water. A hydrochloric acid solution, HCℓ(aq), of concentration 0,1 mol·dm -3 is tit...
22.1 Define the term weak base. (2)
22.2 Write down the formula of the conjugate acid of the carbonate ion, CO3 (aq). (1)
22.3 Determine the value of:
22.3.1 p (1)
22.3.2 q (1)
22.4 METHYL ORANGE is used as the indicator. Explain why methyl orange is the most suitable indicator
22.5 Calculate the concentration of the K2CO3 solution. (Answer: 0,0625 mol∙dm-3) (5)
22.6 Calculate the value of x in the formula K2CO3·xH2O. (Answer: x = 2) (5)
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🔋 Electrochemistry — Galvanic Cells
EMF · cell notation · half-reactions · salt bridge · spontaneity · relative strengths
November 2014
Q1 — Galvanic Cells
A standard electrochemical cell is set up using a standard hydrogen half-cell and a standard X|X2+ half-cell as shown below. A voltmeter connected across the cell, initially registers 0,31 V. Hydrogen...
1.1 Besides concentration write down TWO conditions needed for the hydrogen half-cell to function
1.2 Give TWO reasons, besides being a solid, why platinum is suitable to be used as electrode in the
1.3 Write down the:
1.3.1 NAME of component Q (1)
1.3.2 Standard reduction potential of the X|X2+ half-cell (1)
1.3.3 Half-reaction that takes place at the cathode of this cell (2)
1.4 The hydrogen half-cell is now replaced by a M|M2+ half-cell. The cell notation of this cell is:
1.4.1 Identify metal M. Show how you arrived at the answer. (5)
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March 2015
Q2 — Galvanic Cells
A learner conducts two experiments to investigate the reaction between copper (Cu) and a silver nitrate solution, AgNO3(aq). EXPERIMENT 1 The learner adds a small amount of copper (Cu) powder to a tes...
2.1 Define the term oxidising agent. (2)
2.2 Explain why the solution turns blue by referring to the relative strength of oxidising agents. (4)
2.3 Write down the energy conversion that
2.4 In which direction (A or B) will ANIONS
2.6 Write down the balanced equation for the
2.7 How will the addition of 100 cm3 of a
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2015
Q3 — Galvanic Cells
Learners are given the following two unknown half-cells: Half-cell 1: Q2+ (aq) | Q(s) Half-cell 2: Pt | R2(g) | R-(aq) During an investigation to identify th...
3.1 Write down THREE conditions needed for these cells to function as standard cells. (3)
3.2 For Combination I, identify:
3.2.1 The anode of the cell (1)
3.2.2 Q by using a calculation (Answer: - 0,27 V; Ni / nickel) (5)
3.3 For Combination II, write down the:
3.3.1 Oxidation half-reaction (2)
3.3.2 NAME or FORMULA of the metal used in the cathode compartment (1)
3.4 Arrange the following species in order of INCREASING oxidising ability: Q2+ ; R2 ; Cd2+
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
March 2016
Q4 — Galvanic Cells
An electrochemical cell consisting of half-cells A and B is assembled under standard conditions as shown below. Half-cell A Pt, Cℓ2 (101,3 kPa) | Cℓ- (1 mol∙dm-3) Half-cell B ...
4.1 At which half-cell, A or B, are electrons released into the external circuit? (1)
4.2 Write down the:
4.2.1 Reduction half-reaction that takes place in this cell (2)
4.2.2 NAME or FORMULA of the substance whose oxidation number DECREASES (1)
4.3 Calculate the initial cell potential of this cell when it is in operation. (Answer: 3,72 V) (4)
4.4 Write down an observation that will be made in half-cell B as the cell operates. Give a reason for the
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2016
Q5 — Galvanic Cells
Magnesium (Mg) reacts with a dilute hydrochloric acid solution, HCℓ(aq), according to the following balanced equation: Mg(s) + 2HCℓ(aq) → MgCℓ2(aq) + H2(g) It is found that silver does not react with ...
5.1 Give a reason why the reaction above is a redox reaction. (1)
5.2 Write down the FORMULA of the oxidising agent in the reaction above. (1)
5.3 Refer to the relative strengths of reducing agents to explain this observation. (3)
5.4 What is the function of platinum in the cell above? (1)
5.5 Write down the:
5.5.1 Energy conversion that takes place in this cell (1)
5.5.2 Function of Q (1)
5.5.3 Half-reaction that takes place at the cathode (2)
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November 2016
Q6 — Galvanic Cells
takes place. Nickel (Ni) rod Write down the: Ag Ni
6.1 A nickel (Ni) rod is placed in a beaker containing a silver nitrate solution, AgNO 3(aq) and a reaction
6.1.1 NAME or FORMULA of the electrolyte (1)
6.1.2 Oxidation half-reaction that takes place (2)
6.1.3 Balanced equation for the net (overall) redox reaction that takes place (3)
6.2 A galvanic cell is now set up using a nickel half-cell and a silver half-cell.
6.2.1 Which electrode (Ni or Ag) must be connected to the negative terminal of the voltmeter?
6.2.2 Write down the cell notation for the galvanic cell above. (3)
6.2.3 Calculate the initial reading on the voltmeter if the cell functions under standard conditions. (4)
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Maart 2017
Q7 — Galvanic Cells
In the electrochemical cell shown below an aluminium electrode and another metal electrode, Y, are used. Aℓ Y Aℓ3+(aq) Y2+(aq) It is found that th...
7.1 Write down the:
7.1.1 Name of component Q (1)
7.1.2 Type of electrochemical cell represented above (1)
7.2 How will EACH of the following change while the cell is functioning? Choose from INCREASES,
7.2.1 The concentration of Aℓ3+(aq) (1)
7.2.2 The concentration of Y2+(aq) (1)
7.3 Write down the half-reaction that takes place at electrode Y. (2)
7.4 Write down the cell notation of the cell. (3)
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November 2017
Q8 — Galvanic Cells
HALF-CELL P HALF-CELL Q HALF-CELL R Zn | Zn2+(aq) Cℓ | Cℓ-(aq) Cu | Cu2+(aq) Different combinations of the half-cells above are compared to determine the highest emf p...
8.1 Learners set up a galvanic cell and measure its emf under standard conditions.
8.1.1 Write down the name of component Y. (1)
8.1.2 Is Aℓ the ANODE or the CATHODE? (1)
8.1.3 Write down the overall (net) cell reaction that takes place in this cell when it is working. (3)
8.1.4 Calculate the initial emf of this cell (4)
8.2 Consider the half-cells, P, Q and R, represented in the table below.
8.2.1 Write down the NAME of a suitable electrode for half-cell Q. (1)
8.2.2 State the standard conditions under which the half-cells should operate to ensure a fair
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March 2018
Q9 — Galvanic Cells
Sn2+(aq) + 2Ag+(aq) → 2Ag(s) + Sn4+(aq) learners place magnesium ribbon in a beaker containing a blue solution of copper(II) sulphate. After a while,
9.1 A group of learners use the redox reaction below to construct an electrochemical cell.
9.1.1 Define a reducing agent in terms of electron transfer. (2)
9.1.2 Name a substance that should be used as electrode in the anode half-cell. (1)
9.1.3 Write down the NAME or FORMULA of the reducing agent. (1)
9.1.4 Write down the cell notation of the cell. (3)
9.1.5 Calculate the initial emf of this cell under standard conditions. (4)
9.2 In a separate experiment, the
9.2.1 State ONE observable
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June 2018
Q10 — Galvanic Cells
Pt(s) | Fe2+(aq), Fe3+(aq) || X+(aq) | X(s) The cell potential of this cell was found to be 0,03 V. Write down the:
10.1 Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal:
10.1.1 Write down the type of electrochemical cell illustrated above. (1)
10.1.2 What does the single line (|) in the above cell notation represent? (1)
10.1.3 Write down the half-reaction that takes place at the anode in the above cell. (2)
10.1.4 Identify X with the aid of a calculation. (5)
10.2 A Pt(s) | Fe2+(aq), Fe3+(aq) half-cell is connected to a Cu(s) | Cu2+(aq) half-cell.
10.2.1 Chemical symbol for the electrode in the cathode half-cell (1)
10.2.2 NAME of the oxidising agent (1)
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November 2018
Q11 — Galvanic Cells
corrosion of iron leading to the formation of iron(III) ions. A cleaned copper rod and a cleaned iron nail are placed in a beaker containing water at 25 °C, as shown. After a while it was observed tha...
11.1 Corrosion is a redox reaction that takes place in the presence of oxygen and water. Rusting is the
11.1.1 Define oxidation in terms of electron transfer. (2)
11.1.2 Write down the half-reaction for the iron nail. (2)
11.1.3 Does iron act as REDUCING AGENT or OXIDISING AGENT in the beaker? (1)
11.1.4 Explain the above observation by referring to the Table of Standard Reduction Potentials. (3)
11.1.5 You are given two metals, Zn and Cu, to use as metal Q. Which metal would more
11.2 A galvanic cell is constructed using a Fe | Fe3+ half- cell and a Cu | Cu2+ half-cell.
11.2.1 Write down the overall (net) cell reaction that takes place when the cell is functioning. (3)
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June 2019
Q12 — Galvanic Cells
The electrochemical cell below functions under standard conditions. chlorine gas Q 1 mol·dm-3 Cℓ‒(aq) Cr3+(aq) Half-ce...
12.1 Give a reason why platinum is used as the electrode in half-cell A. (1)
12.2 Write down the:
12.2.1 Energy conversion that takes place in this cell (1)
12.2.2 Half-reaction that takes place at the cathode (2)
12.2.3 Cell notation for this cell (3)
12.3 Calculate the initial emf of this cell. (Answer: 2,10 V) (4)
12.4 Silver chloride is an insoluble salt. What will be the effect on the cell potential when a small amount of
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2019
Q13 — Galvanic Cells
A standard electrochemical cell is set up using two standard half-cells, as shown in the diagram below. Cℓ2(g) Q Cℓ‒(aq) ...
13.1 State the energy conversion that takes place in this cell. (1)
13.2 What is the function of component Q? (1)
13.3 Use a calculation to identify metal X.
13.4 Write down the NAME or FORMULA of the reducing agent. (1)
13.5 The reading on the voltmeter becomes ZERO after this cell operates for several hours.
13.5.1 Give a reason for this reading by referring to the rates of oxidation and reduction
13.5.2 How will the reading on the voltmeter be affected? (Choose from INCREASES, DECREASES
13.5.3 Use Le Chatelier's principle to explain the answer to QUESTION 13.5.2. (2)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2020
Q14 — Galvanic Cells
The electrochemical cell illustrated is set up under standard conditions. flow changes. Fully explain why there is a change in direction of electron flow by referring to the relative strengths of the ...
14.1 Component X completes the circuit in the cell. State ONE other function of component X. (1)
14.2 Define the term anode. (2)
14.3 Identify the anode in this cell. (1)
14.4 Write down the:
14.4.1 Reduction half-reaction that takes place in this cell (2)
14.4.2 NAME or FORMULA of the reducing agent in this cell (1)
14.5 Calculate the initial voltmeter reading of this cell under standard conditions. (Answer: 2,36 V) (4)
14.6 The Mg|Mg2+ half-cell is now replaced by a Cu|Cu2+ half-cell. It is found that the direction of electron
September 2021
Q15 — Galvanic Cells
A galvanic cell at standard conditions is represented by the cell notation below. X and Y are unknown electrodes. X | Zn2+(aq) || Fe3+(aq) , Fe2+(aq) | Y to 0,6 mol·dm-3? Choose from INCREASES, DECREA...
15.1 Write down the NAME or FORMULA of:
15.1.1 Electrode X (1)
15.1.2 Electrode Y (1)
15.1.3 The oxidising agent (1)
15.2 Write down:
15.2.1 ONE function of electrode Y (1)
15.2.2 The half-reaction that takes place at electrode Y (2)
15.2.3 The net (overall) equation for the cell reaction that takes place in this cell (3)
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November 2021
Q16 — Galvanic Cells
The table below shows two half-cells, A and B, used to assemble an electrochemical cell under STANDARD CONDITIONS. Half-cell A Cu2+(aq) | Cu(s) Half-cell B Ag+(aq) | Ag(s)
16.1 State the energy conversion that takes place in this cell. (1)
16.2 Calculate the mass of silver nitrate, AgNO3, used to prepare 150 cm3 of the electrolyte solution in
16.3 Define the term reducing agent. (2)
16.4 Write down the:
16.4.1 NAME or FORMULA of the reducing agent (1)
16.4.2 Balanced equation for the reaction that takes place (3)
16.5 Calculate the initial emf of this cell. (Answer: 0,46 V) (4)
16.6 How will the emf of the cell be affected if the concentration of the copper ions in half-cell A
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2022
Q17 — Galvanic Cells
The initial emf measured under standard conditions is 2,89 V. (Answer: 1,23 V; Oxygen) (5) Ni2+? Refer to the Table of Standard Re...
17.1 An electrochemical cell is set up using an aluminium rod, Aℓ, and a gas X.
17.1.1 State the standard conditions under which this cell operates. (3)
17.1.2 Use a calculation to identify gas X.
17.1.3 Write down the FORMULA of the reducing agent in this cell. (1)
17.1.4 Write down the half-reaction that takes place at the cathode. (2)
17.1.5 Write down the cell notation for this cell. (3)
17.2 Which container, ZINC or COPPER, will be more suitable to store an aqueous solution of nickel ions,
November 2022
Q18 — Galvanic Cells
After some time, it is found that a redox reaction has taken place. Use the Table of Standard Reduction Potentials to answer the following questions: has taken place. ...
18.1 A piece of zinc (Zn) is placed in a test tube containing an acidified permanganate solution, MnO─(aq).
18.1.1 Write down the NAME or FORMULA of the reducing agent. (1)
18.1.2 Refer to the relative strengths of the OXIDISING AGENTS to explain why a redox reaction
18.2 A standard electrochemical cell is set up as shown below.
18.2.1 Write down the function of
18.2.2 In which direction will electrons flow
18.2.3 Calculate the initial emf of this cell.
18.2.4 Write down the balanced equation
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June 2023
Q19 — Galvanic Cells
Learners want to identify an unknown metal X using a standard half-cell, X│X2+. They set up an electrochemical cell under standard conditions using two half-cells, as shown in the diagram The initial ...
19.1 State the standard conditions under which this cell functions. (3)
19.2 State ONE function of component Y. (1)
19.3 Identify X by means of a suitable calculation. (5)
19.4 Write down the oxidation half-reaction that takes place in this cell. (2)
19.5 Arrange the oxidising agents, X2+, Au3+ and H+, in order of increasing strength.
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November 2023
Q20 — Galvanic Cells
A cleaned pure copper strip, Cu(s), is placed in a beaker containing a colourless silver nitrate solution, AgNO3(aq), at 25 °C, as shown below. After a while, it is observed that the solution in the b...
20.1 Write down:
20.1.1 ONE other OBSERVABLE change, besides the solution turning blue (1)
20.1.2 The NAME or FORMULA of the oxidising agent (1)
20.2 Explain the answer to QUESTION 20.1.1 by referring to the relative strengths of the oxidising agents
20.3 Write down the:
20.3.1 NAME or FORMULA of electrode A (1)
20.3.2 NAME or FORMULA of solution B (1)
20.3.3 Overall (net) balanced equation for the cell reaction (3)
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June 2024
Q21 — Galvanic Cells
The relationship between the concentration of the electrolyte and the cell potential is investigated using the following electrochemical cell represented by the cell notation: Aℓ(s) | Aℓ3+(aq) || M2+(...
21.1 Identify the reducing agent in this cell. (1)
21.2 Determine the concentration of M2+(aq) that will produce an emf of 1,87 V. (Answer: 0,325 mol∙dm-3) (2)
21.3 How will the concentration of M2+(aq) be affected as the cell operates? Choose from INCREASES,
21.4 Potassium nitrate, KNO3(aq), is used in the salt bridge of this cell.
21.5 Identify metal M with the aid of a calculation. (Answer: 0,34 V; copper) (6)
21.6 Metal M is now replaced with magnesium, Mg.
21.6.1 Which electrode, Aℓ or Mg, will be the anode? (1)
21.6.2 Refer to the relative strengths of the oxidising agents to explain the answer. (2)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2024
Q22 — Galvanic Cells
balanced equation: Mg(s) + 2HCℓ(aq) → MgCℓ2(aq) + H2(g) reaction. (2) It is observed that dilute hydrochloric acid...
22.1 Dilute hydrochloric acid, HCℓ(aq), reacts with magnesium, Mg(s), at 25 °C according to the following
22.1.1 Use oxidation numbers for EACH of the reactants and explain why this reaction is a redox
22.1.2 Write down the FORMULA of the oxidising agent in this reaction. (1)
22.1.3 Explain this observation by referring to the relative strengths of the reducing agents. (2)
22.1.4 Will dilute nitric acid, HNO3(aq), react with copper, Cu(s), at 25 °C? Choose from YES or NO.
22.2 A galvanic cell is represented by the following cell notation:
22.2.1 Write down the balanced net ionic equation for this cell. (3)
22.2.2 How will this affect the initial emf of the cell? Choose from INCREASES, DECREASES or
⚡ Electrochemistry — Electrolytic Cells
Faraday · chlor-alkali · electroplating · product prediction · oxidation numbers
November 2014
Q1 — Electrolytic Cells
The simplified diagrams below represent two electrochemical cells, A and B. A concentrated copper(II) chloride solution is used as electrolyte in both cells. ELECTROCHEMICAL CELL A ...
1.1 Are A and B ELECTROLYTIC or GALVANIC cells? (1)
1.2 Which of the electrodes (P, Q, R or T) will show a mass increase? Write down a half-reaction to
1.3 Write down the NAME or FORMULA of the product formed at:
1.3.1 Electrode P (1)
1.3.2 Electrode R (1)
1.4 Fully explain the answer to QUESTION 1.3.2 by referring to the relative strengths of the reducing
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
March 2015
Q2 — Electrolytic Cells
The apparatus below is used to demonstrate the electrolysis of a concentrated sodium chloride solution. Both electrodes are made of carbon. A few drops of universal indicator are added to the electrol...
2.1 Define the term electrolyte. (2)
2.2 Write down the half-reaction that takes place at electrode Y. (2)
2.3 Write down the NAME or FORMULA of the gas released at electrode X. (1)
2.4 Refer to the Table of Standard Reduction Potentials to explain why hydrogen gas, and not sodium, is
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2015
Q3 — Electrolytic Cells
The diagram shows a simplified electrolytic cell that can be used to electroplate a plastic ring with nickel. Prior to electroplating the ring is covered with a graphite layer. Plastic ring ...
3.1 Define the term electrolyte. (2)
3.2 Give ONE reason why the plastic ring must be coated with graphite prior to electroplating. (1)
3.3 Write down the half-reaction that occurs at the plastic ring. (2)
3.4 Write down the NAME or FORMULA of the reducing agent in the cell. Give a reason for the answer. (2)
3.5 Which electrode, the RING or NICKEL, is the cathode? Give a reason for the answer. (2)
3.6 How will the concentration of the electrolyte change during electroplating? Write down only
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March 2016
Q4 — Electrolytic Cells
The electrochemical cell below is set up to demonstrate the purification of copper. The graphs below show the change in mass of the electrodes whilst the cell is in operation. B ...
4.1 Write down the type of electrochemical cell illustrated. (1)
4.2 Define a reducing agent in terms of electron transfer. (2)
4.3 Which graph represents the change in mass of electrode A? (1)
4.4 Write down the half-reaction that takes place at electrode A. (2)
4.5 Electrodes A and B are now replaced by graphite electrodes. It is observed that chlorine gas (Cℓ2) is
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2016
Q5 — Electrolytic Cells
The diagram below shows an electrochemical cell used to purify copper. A solution that conducts electricity is used in the cell. A B DECREASES or REMAINS THE SAME. ...
5.1 Write down:
5.1.1 ONE word for the underlined phrase above the diagram (1)
5.1.2 The type of electrochemical cell illustrated above. (1)
5.2 In which direction (from A to B or from B to A) will electrons flow in the external circuit? (1)
5.3 Which electrode (A or B) is the:
5.3.1 Cathode (1)
5.3.2 Impure copper (1)
5.4 How will the mass of electrode A change as the reaction proceeds? Choose from INCREASES,
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June 2017
Q6 — Electrolytic Cells
The simplified diagram below represents a cell used to electroplate an iron medal with a thin layer of gold. medal with silver instead of gold. ...
6.1 Is this an ELECTROLYTIC or a GALVANIC cell? (1)
6.2 Which electrode, P or the Medal, is the anode? (1)
6.3 Write down the:
6.3.1 Half-reaction that takes place at electrode P (2)
6.3.2 Oxidation number of gold (Au) in the electrolyte (1)
6.3.3 Energy change that takes place in this cell (1)
6.3.4 Visible change that occurs on electrode P after the cell functions for a while (1)
6.4 Besides improving appearance, state ONE other reason why the medal is electroplated. (1)
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November 2017
Q7 — Electrolytic Cells
The simplified diagram represents an electrochemical cell used in the refining of copper. One of the electrodes consists of impure copper. Is electrode P the CATHODE or the ANODE? Write down the relev...
7.1 What type of power source, AC or DC, is used to drive the reaction in this cell? (1)
7.2 When an electric current passes through the CuCℓ2(aq), the mass of electrode P increases.
7.3 The impure copper contains zinc impurities which are oxidised to zinc ions. Refer to the relative
7.4 Electrodes P and Q are now replaced by carbon electrodes.
7.4.1 What will be observed at electrode Q? (1)
7.4.2 How will the concentration of the electrolyte change as the reaction proceeds? Choose
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
March 2018
Q8 — Electrolytic Cells
The graph represents the changes in mass that occur at electrode A and electrode B in an electrolytic cell during the purification of copper. (Answer: 88%) ...
8.1 Define electrolysis. (2)
8.2 Which graph, A or B, represents the change in mass of the anode during electrolysis? (1)
8.3 Write down the equation of the half-reaction which takes place at the cathode of this cell. (2)
8.4 Use the information in the graph and calculate the percentage purity of the impure copper.
June 2018
Q9 — Electrolytic Cells
The diagram below shows an electrolytic cell used to electroplate an iron rod with COPPER. Solution X is made up of an unknown NITRATE. a while, TWO metallic ions are found to be present in the soluti...
9.1 Solutions, such as solution X, are always used in electrochemical cells.
9.1.1 Write down the general term used to describe these solutions. (1)
9.1.2 What is the function of these solutions in electrochemical cells? (1)
9.2 Write down the FORMULA of solution X. (1)
9.3 Which electrode (A or IRON ROD) is the negative electrode? Give a reason for the answer. (2)
9.4 Write down the half-reaction that takes place at electrode A. (2)
9.5 Electrode A is now replaced by a silver rod without making any other changes to the cell. After
9.5.1 Name the TWO metallic ions present in the solution. (2)
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November 2018
Q10 — Electrolytic Cells
The electrolytic cell below is set up to obtain pure copper from a piece of impure copper. The impure copper contains other metals, such as platinum, iron, cobalt, silver and nickel. The cell potentia...
10.1 Define an electrolytic cell. (2)
10.2 Write down the FORMULA of a suitable
10.3 Which electrode (A or B) is the cathode? Write down the relevant half-reaction taking place at
10.4 Sludge forms below one of the electrodes while the cell above is in operation. Which of the metals,
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2019
Q11 — Electrolytic Cells
The diagrams below represent two electrochemical cells. P, Q, X and Y are carbon electrodes. Cell A Cell B P Q X ...
11.1 What type of electrochemical cell, GALVANIC or ELECTROLYTIC, is illustrated above? (1)
11.2 Write down the half-reaction that takes place at electrode Q. (2)
11.3 The products formed in the two cells are compared.
11.3.1 Name ONE substance that is produced in BOTH cells. (1)
11.3.2 Write down the LETTERS of the TWO electrodes where this product is formed.
11.4 Is electrode X the CATHODE or the ANODE? Give a reason for the answer. (2)
11.5 Write down the net (overall) cell reaction that takes place in cell B. (3)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2019
Q12 — Electrolytic Cells
Chlorine is produced industrially by the electrolysis of a concentrated sodium chloride solution, NaCℓ(aq). The balanced equation for the net (overall) cell reaction is as follows: 2NaCℓ(aq) + 2H2O(ℓ)...
12.1 Define the term electrolysis. (2)
12.2 For the above reaction, write down the:
12.2.1 Half-reaction that takes place at the cathode (2)
12.2.2 NAME or FORMULA of the oxidising agent (1)
12.3 Refer to the Table of Standard Reduction Potentials to explain why sodium ions are not reduced
November 2020
Q13 — Electrolytic Cells
The simplified diagram below represents an electrolytic cell used to electroplate a copper (Cu) coin with silver (Ag). DECREASES or REMAINS THE SAME. Give a reason for the answer. ...
13.1 Define the term electrolysis. (2)
13.2 Which component in the diagram indicates that this is an electrolytic cell? (1)
13.3 Write down the NAME or FORMULA of the electrolyte. (1)
13.4 How will the concentration of the electrolyte change during electroplating? Choose from INCREASES,
13.5 Write down the balanced equation of the half-reaction that takes place at the silver electrode. (2)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2021
Q14 — Electrolytic Cells
The diagrams below show two electrochemical cells in which carbon electrodes are used. In cell A, concentrated copper (II) chloride solution is used and in cell B, liquid aluminium oxide is used. for ...
14.1 What type of electrochemical cell, ELECTROLYTIC or GALVANIC, is shown above? Give a reason
14.2 Write down the:
14.2.1 Half-reaction that takes place at the anode of cell A (2)
14.2.2 Half-reaction that takes place at the cathode of cell B (2)
14.2.3 NAME or FORMULA of the product formed at the cathode of cell A (1)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
September 2021
Q15 — Electrolytic Cells
The simplified diagram below represents an electrochemical cell used for the purification of copper. The impure copper contains small amounts of silver (Ag) and zinc (Zn) as the only impurities. conta...
15.1 Define the term electrolysis. (2)
15.2 Write down the NAME or FORMULA of TWO positive ions present in the electrolyte. (2)
15.3 Write down the half-reaction that takes place at the cathode. (2)
15.4 Refer to the Table of Standard Reduction Potentials and explain why the purified copper will NOT
15.5 Calculate the maximum mass of Cu formed if 0,6 moles of electrons are transferred.
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November 2021
Q16 — Electrolytic Cells
The diagram below shows a simplified electrolytic cell used to electroplate a ring. (Answer: 11 076,8 to 11 580 C) (5)
16.1 Define the term electrolyte. (2)
16.2 Is the pure chromium metal the ANODE or the CATHODE of the cell? Give a reason for the answer. (2)
16.3 Write down the half-reaction that takes place at the ring. (2)
16.4 Calculate the total charge transferred when the mass of the pure chromium changes by 2 g.
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2022
Q17 — Electrolytic Cells
The simplified diagram on the right represents an electrochemical cell used for the electrolysis of a concentrated sodium chloride solution, NaCℓ(aq). X and Y are carbon electrodes. Choose from INCREA...
17.1 Define the term electrolysis. (2)
17.2 Chlorine gas, Cℓ2(g), is released at electrode X. Write down the:
17.2.1 Letter (X or Y) of the electrode where oxidation takes place (1)
17.2.2 Half-reaction that takes place at electrode Y (2)
17.2.3 Direction in which electrons flow in the external circuit. Choose from X to Y OR Y to X. (1)
17.2.4 Balanced equation for the net (overall) cell reaction that takes place in the cell (3)
17.3 How will the pH of the electrolyte change during the reaction?
17.4 Give a reason for the answer to QUESTION 17.3. (1)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2023
Q18 — Electrolytic Cells
The simplified electrolytic cell below is used to electroplate a metal spring. Zinc nitrate, Zn(NO3)2(aq), is used as an electrolyte and R is an electrode.
18.1 Define the term electrolytic cell. (2)
18.2 Which electrode (R or METAL SPRING) is the ANODE? Give a reason for the answer. (2)
18.3 Write down the:
18.3.1 Equation for the half-reaction occurring at the metal spring (2)
18.3.2 NAME or FORMULA of a suitable metal that can be used as electrode R (1)
18.4 Explain the answer to QUESTION 18.3.2. (2)
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2023
Q19 — Electrolytic Cells
An electrolytic cell is set up to purify a piece of copper that contains silver and zinc as impurities. A simplified diagram of the cell is shown below. Electrode R is impure copper. (Answer: 2,68 A) ...
19.1 Define the term electrolysis. (2)
19.2 Write down the reaction taking place at electrode Q. (2)
19.3 In which direction do the electrons flow in the external circuit? Choose from Q to R or R to Q. (1)
19.4 Calculate the current needed to form 16 g of copper when the cell operates for five hours.
19.5 During this electrolysis, only copper and zinc are oxidised.
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
June 2024
Q20 — Electrolytic Cells
The simplified diagram below represents the cell used for electroplating ornaments with silver, Ag. P and Q are the two terminals of the battery. cell. (...
20.1 State the energy conversion that takes place in this
20.2 Which terminal of the battery (P or Q) is negative? (1)
20.3 Write down the equation for the half-cell reaction
20.4 Calculate the current needed to electroplate the
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.
November 2024
Q21 — Electrolytic Cells
Consider the following reaction: 2Ag(s) + Pb2+(aq) → 2Ag+(s) + Pb(s) By means of a calculation, determine whether this reaction is SPONTANEOUS or NON- SPONTANEOUS. (Answer: - 0,93 V; non-spontaneous) ...
21.1 A strip of silver is added to a 1 mol·dm-3 solution of Pb(NO3)2 at 25 °C.
21.2 The simplified diagram below represents an electrolytic cell. The electrodes are made of carbon.
21.2.1 Define an electrolyte. (2)
21.2.2 Write down the PREDOMINANT oxidation
21.2.3 Write down the NAMES or FORMULAE of the
21.2.4 Explain the answer to QUESTION 21.2.3 by referring
⚠️ Some subquestions refer to a diagram/graph/table in the original paper. Obtain the original NSC paper for full context.