Chemistry A (H032, H432)
H432/03, Unified chemistry (AS/Alevel), June 2024
Kevin Chatten
Please note that you may see slight differences between
this paper and the original.
Duration: 90 mins
Candidates answer on the Question paper.
OCR supplied materials:
Additional resources may be supplied with this paper.
Other materials required:
• Pencil
• Ruler (cm/mm)
INSTRUCTIONS TO CANDIDATES
• Write your name, centre number and candidate number in the boxes above. Please write clearly and in capital letters.
• Use black ink. HB pencil may be used for graphs and diagrams only.
• Answer all the questions, unless your teacher tells you otherwise.
• Read each question carefully. Make sure you know what you have to do before starting your answer.
• Where space is provided below the question, please write your answer there.
• You may use additional paper, or a specific Answer sheet if one is provided, but you must clearly show your candidate
number, centre number and question number(s).
INFORMATION FOR CANDIDATES
• The quality of written communication is assessed in questions marked with either a pencil or an asterisk. In History and
Geography a Quality of extended response question is marked with an asterisk, while a pencil is used for questions in
which Spelling, punctuation and grammar and the use of specialist terminology is assessed.
• The number of marks is given in brackets [ ] at the end of each question or part question.
• The total number of marks for this paper is 70.
• The total number of marks may take into account some 'either/or' question choices.
© OCR 2025. You may photocopy this page. 1 of 52 Created in ExamBuilder
, 1(a) What is the pH of 1.00 dm3 of 0.400 mol dm–3 of NaOH(aq) at 298 K?
pH = ................................................... [2]
3 -3
(b) Water is added to 10.0 cm of 0.750 mol dm HCl (aq) to produce 100 cm3 of diluted HCl (aq).
What is the pH of the diluted HCl (aq)?
Give your answer to 2 decimal places.
pH = ................................................... [1]
(c) A solution has concentrations of 0.300 mol dm CH3COOH(aq) and 0.100 mol dm–3 CH3COONa(aq).
–3
Ka for CH3COOH = 1.75 × 10–5 mol dm–3 at 298 K.
What is the pH of the solution at 298 K?
Give your answer to 2 decimal places.
pH = ................................................... [2]
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, (d) A student is provided with hydrated copper(II) nitrate, Cu(NO3)2•3H2O.
The student needs to prepare a standard solution of Cu(NO3)2•3H2O with a concentration of 0.200 mol dm–3. The
student has access to usual laboratory apparatus and equipment.
Describe how the student would prepare 100.0 cm3 of this solution, giving quantities, apparatus and method.
[5]
© OCR 2025. You may photocopy this page. 3 of 52 Created in ExamBuilder
, 2(a) Hydrogen gas is manufactured by the chemical industry from the reversible reaction of methane and steam,
shown below.
CH4(g) + H2O(g) ⇌ 3H2(g) + CO(g) ΔH = +195 kJ mol–1
Average bond enthalpies are shown in the table.
Bond H–H O–H C=O
–1
Average bond enthalpy / kJ mol +436 +464 +1077
i. Why do all average bond enthalpies have a positive value?
[1]
ii. Determine the C–H bond enthalpy, in kJ mol–1, using the information above.
C–H bond enthalpy = ................................................... kJ mol–1[3]
iii. Hydrogen gas is being considered as a household fuel to replace methane.
The enthalpy change of formation, ΔfH, for H2O(l) is –285.8 kJ mol–1.
Determine the energy released when 60.0 m3 of hydrogen is used as a household fuel at RTP.
Give your answer to 3 significant figures and in standard form.
energy released = ................................................... kJ [2]
© OCR 2025. You may photocopy this page. 4 of 52 Created in ExamBuilder
H432/03, Unified chemistry (AS/Alevel), June 2024
Kevin Chatten
Please note that you may see slight differences between
this paper and the original.
Duration: 90 mins
Candidates answer on the Question paper.
OCR supplied materials:
Additional resources may be supplied with this paper.
Other materials required:
• Pencil
• Ruler (cm/mm)
INSTRUCTIONS TO CANDIDATES
• Write your name, centre number and candidate number in the boxes above. Please write clearly and in capital letters.
• Use black ink. HB pencil may be used for graphs and diagrams only.
• Answer all the questions, unless your teacher tells you otherwise.
• Read each question carefully. Make sure you know what you have to do before starting your answer.
• Where space is provided below the question, please write your answer there.
• You may use additional paper, or a specific Answer sheet if one is provided, but you must clearly show your candidate
number, centre number and question number(s).
INFORMATION FOR CANDIDATES
• The quality of written communication is assessed in questions marked with either a pencil or an asterisk. In History and
Geography a Quality of extended response question is marked with an asterisk, while a pencil is used for questions in
which Spelling, punctuation and grammar and the use of specialist terminology is assessed.
• The number of marks is given in brackets [ ] at the end of each question or part question.
• The total number of marks for this paper is 70.
• The total number of marks may take into account some 'either/or' question choices.
© OCR 2025. You may photocopy this page. 1 of 52 Created in ExamBuilder
, 1(a) What is the pH of 1.00 dm3 of 0.400 mol dm–3 of NaOH(aq) at 298 K?
pH = ................................................... [2]
3 -3
(b) Water is added to 10.0 cm of 0.750 mol dm HCl (aq) to produce 100 cm3 of diluted HCl (aq).
What is the pH of the diluted HCl (aq)?
Give your answer to 2 decimal places.
pH = ................................................... [1]
(c) A solution has concentrations of 0.300 mol dm CH3COOH(aq) and 0.100 mol dm–3 CH3COONa(aq).
–3
Ka for CH3COOH = 1.75 × 10–5 mol dm–3 at 298 K.
What is the pH of the solution at 298 K?
Give your answer to 2 decimal places.
pH = ................................................... [2]
© OCR 2025. You may photocopy this page. 2 of 52 Created in ExamBuilder
, (d) A student is provided with hydrated copper(II) nitrate, Cu(NO3)2•3H2O.
The student needs to prepare a standard solution of Cu(NO3)2•3H2O with a concentration of 0.200 mol dm–3. The
student has access to usual laboratory apparatus and equipment.
Describe how the student would prepare 100.0 cm3 of this solution, giving quantities, apparatus and method.
[5]
© OCR 2025. You may photocopy this page. 3 of 52 Created in ExamBuilder
, 2(a) Hydrogen gas is manufactured by the chemical industry from the reversible reaction of methane and steam,
shown below.
CH4(g) + H2O(g) ⇌ 3H2(g) + CO(g) ΔH = +195 kJ mol–1
Average bond enthalpies are shown in the table.
Bond H–H O–H C=O
–1
Average bond enthalpy / kJ mol +436 +464 +1077
i. Why do all average bond enthalpies have a positive value?
[1]
ii. Determine the C–H bond enthalpy, in kJ mol–1, using the information above.
C–H bond enthalpy = ................................................... kJ mol–1[3]
iii. Hydrogen gas is being considered as a household fuel to replace methane.
The enthalpy change of formation, ΔfH, for H2O(l) is –285.8 kJ mol–1.
Determine the energy released when 60.0 m3 of hydrogen is used as a household fuel at RTP.
Give your answer to 3 significant figures and in standard form.
energy released = ................................................... kJ [2]
© OCR 2025. You may photocopy this page. 4 of 52 Created in ExamBuilder
