Chemistry A (H032, H432)
H032/02, Depth in chemistry (A level), June 2024
Neil Bechley
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 45 Created in ExamBuilder
, 1(a) Hydrogen and oxygen have different electronegativities.
What is meant by the term electronegativity?
[2]
(b) H2O is a polar molecule that has hydrogen bonding.
i. Complete the diagram below to show hydrogen bonding between the H2O molecule shown and another H2O
molecule.
Include relevant dipoles and lone pairs.
Label the hydrogen bond.
[2]
ii. Explain why molecules of H2O are polar.
[1]
iii. One unusual property of H2O is that ice floats on water.
Explain why ice has a lower density than water.
[1]
© OCR 2025. You may photocopy this page. 2 of 45 Created in ExamBuilder
, (c) Solid ammonia, NH3, contains hydrogen bonds.
i. Suggest why solid ammonia has a lower melting point than ice.
[2]
ii. When ammonia dissolves in water, ammonium ions, NH4+, are formed.
Draw a ‘dot-and-cross’ diagram to show the bonding in an NH4+ ion.
Show outer electrons only.
[2]
iii. Outline how you would test for the presence of NH4+ ions in a solution.
Your answer should include observations.
[2]
(d) A student heats 11.50 g of hydrated zinc sulfate, ZnSO4·7H2O, to remove all the water of crystallisation.
Calculate the mass of anhydrous zinc sulfate that should be obtained.
mass = ....................................................... g [3]
© OCR 2025. You may photocopy this page. 3 of 45 Created in ExamBuilder
, 2(a) This question is about periodicity and the reaction of some Group 2 metals.
Periodicity is the repeating trend in properties of elements across different periods in the periodic table.
i. Complete the table below with the electron configurations and blocks.
Group 2 Group 17 (7)
Period 2 Be F
1s2 ........................................................ 1s2 ........................................................
Period 3 Mg Cl
1s2 ........................................................ 1s2 ........................................................
Block ............................. .............................
[3]
ii. Use your answers to (i) to explain why electron configuration is an example of a periodic trend.
[2]
iii. Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why.
[2]
iv. Magnesium reacts with oxygen in the air.
Write the equation for this reaction.
[1]
© OCR 2025. You may photocopy this page. 4 of 45 Created in ExamBuilder
, (b) The reaction between calcium and hydrochloric acid is a redox reaction.
Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g) Equation 2.1
i. Explain, in terms of electron transfer, why the reaction shown in equation 2.1 is a redox reaction.
[2]
ii. A student plans to add 0.0100 mol of Ca to 120 cm3 of 0.100 mol dm–3 HCl (aq).
When the student carries out this reaction, they are surprised that all the calcium reacts, despite being in
excess of the HCl(aq).
• Show by calculation that calcium is in excess of the HCl(aq).
• Suggest a reason for this unexpected result.
[3]
© OCR 2025. You may photocopy this page. 5 of 45 Created in ExamBuilder
, (c) The graph shows the first ionisation energies for the elements Li to Be and for C to Na.
i. Complete the graph by adding points for the missing values of B and Mg.
[2]
ii. Write an equation, including state symbols, to represent the second ionisation energy of B.
[2]
3(a) Enthalpy changes of reaction can be determined by experiment.
What is meant by the term enthalpy change of reaction?
[1]
© OCR 2025. You may photocopy this page. 6 of 45 Created in ExamBuilder
, (b) A student carries out an experiment to determine the enthalpy change for the reaction between zinc and
copper(II) nitrate solution.
Zn(s) + Cu(NO3)2(aq) → Zn(NO3)2(aq) + Cu(s) ΔrH Equation 3.1
The student follows the method outlined below.
• Add 100 cm3 of 0.500 mol dm-3 Cu(NO3)2(aq) to a beaker.
• Measure the temperature of the solution.
• Add excess zinc to the beaker.
• Stir the mixture and record the maximum temperature.
The temperature of the solution changes from 19.5 °C to 38.1 °C.
Calculate ΔrH, in kJ mol-1, for equation 3.1.
State any assumptions you have made in your calculation.
Suggest improvements for obtaining a more accurate value for ΔrH.
© OCR 2025. You may photocopy this page. 7 of 45 Created in ExamBuilder
, [6]
© OCR 2025. You may photocopy this page. 8 of 45 Created in ExamBuilder
, (c) The student modifies the experiment using 50 cm3 instead of 100 cm3 of 0.500 mol dm-3 copper(II) nitrate
solution.
The value of ΔrH for this modified experiment is the same as in equation 3.1.
Explain why.
[2]
© OCR 2025. You may photocopy this page. 9 of 45 Created in ExamBuilder
, 4(a) Aqueous hydrogen peroxide, H2O2(aq), gradually decomposes to produce water and oxygen.
2H2O2(aq) → 2H2O(l) + O2(g) ΔH=-196 kJ mol-1 Equation 4.1
The rate of decomposition of H2O2 can be increased by adding a small amount of manganese(IV) oxide, MnO2,
which acts as a catalyst.
Explain, using a Boltzmann distribution model, why the rate of a reaction increases in the presence of a catalyst.
You are provided with the axes below, which you should label.
[4]
© OCR 2025. You may photocopy this page. 10 of 45 Created in ExamBuilder
H032/02, Depth in chemistry (A level), June 2024
Neil Bechley
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 45 Created in ExamBuilder
, 1(a) Hydrogen and oxygen have different electronegativities.
What is meant by the term electronegativity?
[2]
(b) H2O is a polar molecule that has hydrogen bonding.
i. Complete the diagram below to show hydrogen bonding between the H2O molecule shown and another H2O
molecule.
Include relevant dipoles and lone pairs.
Label the hydrogen bond.
[2]
ii. Explain why molecules of H2O are polar.
[1]
iii. One unusual property of H2O is that ice floats on water.
Explain why ice has a lower density than water.
[1]
© OCR 2025. You may photocopy this page. 2 of 45 Created in ExamBuilder
, (c) Solid ammonia, NH3, contains hydrogen bonds.
i. Suggest why solid ammonia has a lower melting point than ice.
[2]
ii. When ammonia dissolves in water, ammonium ions, NH4+, are formed.
Draw a ‘dot-and-cross’ diagram to show the bonding in an NH4+ ion.
Show outer electrons only.
[2]
iii. Outline how you would test for the presence of NH4+ ions in a solution.
Your answer should include observations.
[2]
(d) A student heats 11.50 g of hydrated zinc sulfate, ZnSO4·7H2O, to remove all the water of crystallisation.
Calculate the mass of anhydrous zinc sulfate that should be obtained.
mass = ....................................................... g [3]
© OCR 2025. You may photocopy this page. 3 of 45 Created in ExamBuilder
, 2(a) This question is about periodicity and the reaction of some Group 2 metals.
Periodicity is the repeating trend in properties of elements across different periods in the periodic table.
i. Complete the table below with the electron configurations and blocks.
Group 2 Group 17 (7)
Period 2 Be F
1s2 ........................................................ 1s2 ........................................................
Period 3 Mg Cl
1s2 ........................................................ 1s2 ........................................................
Block ............................. .............................
[3]
ii. Use your answers to (i) to explain why electron configuration is an example of a periodic trend.
[2]
iii. Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why.
[2]
iv. Magnesium reacts with oxygen in the air.
Write the equation for this reaction.
[1]
© OCR 2025. You may photocopy this page. 4 of 45 Created in ExamBuilder
, (b) The reaction between calcium and hydrochloric acid is a redox reaction.
Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g) Equation 2.1
i. Explain, in terms of electron transfer, why the reaction shown in equation 2.1 is a redox reaction.
[2]
ii. A student plans to add 0.0100 mol of Ca to 120 cm3 of 0.100 mol dm–3 HCl (aq).
When the student carries out this reaction, they are surprised that all the calcium reacts, despite being in
excess of the HCl(aq).
• Show by calculation that calcium is in excess of the HCl(aq).
• Suggest a reason for this unexpected result.
[3]
© OCR 2025. You may photocopy this page. 5 of 45 Created in ExamBuilder
, (c) The graph shows the first ionisation energies for the elements Li to Be and for C to Na.
i. Complete the graph by adding points for the missing values of B and Mg.
[2]
ii. Write an equation, including state symbols, to represent the second ionisation energy of B.
[2]
3(a) Enthalpy changes of reaction can be determined by experiment.
What is meant by the term enthalpy change of reaction?
[1]
© OCR 2025. You may photocopy this page. 6 of 45 Created in ExamBuilder
, (b) A student carries out an experiment to determine the enthalpy change for the reaction between zinc and
copper(II) nitrate solution.
Zn(s) + Cu(NO3)2(aq) → Zn(NO3)2(aq) + Cu(s) ΔrH Equation 3.1
The student follows the method outlined below.
• Add 100 cm3 of 0.500 mol dm-3 Cu(NO3)2(aq) to a beaker.
• Measure the temperature of the solution.
• Add excess zinc to the beaker.
• Stir the mixture and record the maximum temperature.
The temperature of the solution changes from 19.5 °C to 38.1 °C.
Calculate ΔrH, in kJ mol-1, for equation 3.1.
State any assumptions you have made in your calculation.
Suggest improvements for obtaining a more accurate value for ΔrH.
© OCR 2025. You may photocopy this page. 7 of 45 Created in ExamBuilder
, [6]
© OCR 2025. You may photocopy this page. 8 of 45 Created in ExamBuilder
, (c) The student modifies the experiment using 50 cm3 instead of 100 cm3 of 0.500 mol dm-3 copper(II) nitrate
solution.
The value of ΔrH for this modified experiment is the same as in equation 3.1.
Explain why.
[2]
© OCR 2025. You may photocopy this page. 9 of 45 Created in ExamBuilder
, 4(a) Aqueous hydrogen peroxide, H2O2(aq), gradually decomposes to produce water and oxygen.
2H2O2(aq) → 2H2O(l) + O2(g) ΔH=-196 kJ mol-1 Equation 4.1
The rate of decomposition of H2O2 can be increased by adding a small amount of manganese(IV) oxide, MnO2,
which acts as a catalyst.
Explain, using a Boltzmann distribution model, why the rate of a reaction increases in the presence of a catalyst.
You are provided with the axes below, which you should label.
[4]
© OCR 2025. You may photocopy this page. 10 of 45 Created in ExamBuilder
