OCR A-Level Chemistry Periodic table, elements and physical chemistry (01), June 2025
Every question from OCR A-Level Chemistry Periodic table, elements and physical chemistry (01), June 2025 (H432): 21 questions, 100 marks, each with its mark scheme and topic.
- Question 1 1 mark
Identify which two atoms from a given table of proton and neutron numbers are isotopes of the same element.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 2 1 mark
Calculate the value of x in the formula of hydrated cobalt(II) chloride, CoCl2•xH2O, given the mass before and after heating to constant mass.
Module 2: Foundations in chemistry · Practical Activity Groups · 2.1 Atoms and reactions · PAG 1: Moles determination
- Question 3 1 mark
Explain why the second electron affinity of oxygen is an endothermic (positive) value.
Module 5: Physical chemistry and transition elements · 5.2 Energy
- Question 4 1 mark
Calculate the volume in cm³ of 0.250 mol dm⁻³ barium hydroxide required to neutralise 25.0 cm³ of 0.115 mol dm⁻³ hydrochloric acid.
Module 2: Foundations in chemistry · 2.1 Atoms and reactions
- Question 5 1 mark
Determine the rate of reaction at 30 seconds from a graph of volume of hydrogen released against time.
Module 1: Development of practical skills in chemistry · Module 3: Periodic table and energy · Module 5: Physical chemistry and transition elements · Practical Activity Groups · 1.1 Practical skills assessed in a written examination · 3.2 Physical chemistry · 5.1 Rates, equilibrium and pH · PAG 9: Rates of reaction – continuous monitoring method
- Question 6 1 mark
Calculate the C–H bond enthalpy in methane using the given enthalpy change of combustion and bond enthalpies.
Module 3: Periodic table and energy · 3.2 Physical chemistry
- Question 7 1 mark
Identify the best explanation for the increasing trend in boiling points from HCl to HI among hydrogen halides.
Module 2: Foundations in chemistry · Module 3: Periodic table and energy · 2.2 Electrons, bonding and structure · 3.1 The periodic table
- Question 8 1 mark
Calculate the percentage uncertainty of a titre using initial and final burette readings.
Module 1: Development of practical skills in chemistry · Practical Activity Groups · 1.1 Practical skills assessed in a written examination · PAG 2: Acid-base titration
- Question 9 1 mark
Deduce the rate equation for the reaction of hydrogen with iodine monochloride given a two-step mechanism with a slow first step.
Module 5: Physical chemistry and transition elements · 5.1 Rates, equilibrium and pH
- Question 10 1 mark
Identify the correct half-equation at the positive electrode of an alkaline hydrogen-oxygen fuel cell.
Module 5: Physical chemistry and transition elements · 5.2 Energy
- Question 11 1 mark
Identify the strongest reducing agent given the standard electrode potentials of two redox systems.
Module 5: Physical chemistry and transition elements · 5.2 Energy
- Question 12 1 mark
Calculate the half-life of a first-order reaction given a rate constant of 6.19 × 10⁻³ s⁻¹.
Module 5: Physical chemistry and transition elements · 5.1 Rates, equilibrium and pH
- Question 13 1 mark
Identify a suitable indicator pH range for titrating remaining ethanoic acid in an equilibrium mixture with sodium hydroxide solution.
Module 5: Physical chemistry and transition elements · Practical Activity Groups · 5.1 Rates, equilibrium and pH · PAG 2: Acid-base titration
- Question 14 1 mark
Identify which statements are correct regarding the properties, reactivity, and electron configuration of barium compared to magnesium in Group 2.
Module 3: Periodic table and energy · Module 2: Foundations in chemistry · 3.1 The periodic table · 2.2 Electrons, bonding and structure
- Question 15 1 mark
Identify which statements are correct regarding the oxidation states, colours, and coordination numbers of the complex ions [Cr(NH3)6]3+ and [Cr(OH)6]3-.
Module 5: Physical chemistry and transition elements · 5.3 Transition elements
- Question 16 17 marks
Explore Period 3 trends including melting points, first ionisation energy, halogen displacement reactions, and molecular shapes of hydrides.
Module 2: Foundations in chemistry · Module 3: Periodic table and energy · 2.2 Electrons, bonding and structure · 3.1 The periodic table
- Question 17 16 marks
Calculate enthalpy and entropy changes, determine reaction feasibility using Gibbs free energy, and calculate equilibrium partial pressures and analyze temperature dependence using Kp.
Module 3: Periodic table and energy · Module 5: Physical chemistry and transition elements · 3.2 Physical chemistry · 5.1 Rates, equilibrium and pH · 5.2 Energy
- Question 18 14 marks
Explain heterogeneous catalysis using a Boltzmann distribution, determine reaction orders and the rate constant from initial rate data, and plot an Arrhenius graph to calculate activation energy.
Module 1: Development of practical skills in chemistry · Module 3: Periodic table and energy · Module 5: Physical chemistry and transition elements · 1.1 Practical skills assessed in a written examination · 3.2 Physical chemistry · 5.1 Rates, equilibrium and pH
- Question 19 12 marks
Calculate the pH of strong and weak acids, determine oxidation numbers in a disproportionation reaction, and calculate the mass of sodium propanoate required to prepare a buffer solution and explain its action.
Module 2: Foundations in chemistry · Module 5: Physical chemistry and transition elements · 2.1 Atoms and reactions · 5.1 Rates, equilibrium and pH
- Question 20 9 marks
Draw a labelled electrochemical cell diagram, calculate its standard cell potential, and explain the two-stage reduction of VO2+ by cobalt using electrode potentials and equilibrium shifts.
Module 5: Physical chemistry and transition elements · Practical Activity Groups · 5.2 Energy · PAG 8: Electrochemical cells
- Question 21 17 marks
Complete electron configurations, describe precipitation tests, determine an empirical formula and coordination number, draw a stereoisomer, and calculate percentage mass from a redox titration.
Module 1: Development of practical skills in chemistry · Module 2: Foundations in chemistry · Module 5: Physical chemistry and transition elements · 1.1 Practical skills assessed in a written examination · 2.1 Atoms and reactions · 2.2 Electrons, bonding and structure · 5.3 Transition elements