plumiEquilibria: OCR GCSE Chemistry A questions
Every OCR GCSE Chemistry A exam question on C5.3 Equilibria, 2018–2025, with its mark scheme and examiner’s report.
Paper
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Exam
All years
Calculations
Q23(a)
The whole paper ↗Q23(b)(i)
The whole paper ↗- Your answer
- Your answer
Q17(a)
The whole paper ↗Q17(b)(i)
The whole paper ↗Q22(a)(i)
The whole paper ↗Q22(a)(ii)
The whole paper ↗Q22(a)(iii)
The whole paper ↗Q22(b)
The whole paper ↗- Your answer
Q17(a)(i)
The whole paper ↗Q17(a)(ii)
The whole paper ↗Q17(a)(iii)
The whole paper ↗Q17(b)
The whole paper ↗- Your answer
- Your answer
Q21(a)(i)
The whole paper ↗Q21(a)(ii)
The whole paper ↗Q21(b)
The whole paper ↗
All 45 questions on Equilibria, as a list
- June 2025, Paper 2 Foundation, Q23(a) (1 mark): What does the symbol tell you about the reaction? [1]
- June 2025, Paper 2 Foundation, Q23(b)(i) (1 mark): What is the catalyst used? Tick (✓) one box. Iron Manganese(IV) oxide Nickel Platinum [1]
- June 2025, Paper 4 Higher, Q13 (1 mark): The reaction between iodine gas and hydrogen gas reaches equilibrium in a sealed container. Hydrogen iodide is made. The graph shows how the mass of iodine and
- June 2025, Paper 4 Higher, Q15 (1 mark): The reaction between sulfur dioxide gas and oxygen gas reaches equilibrium in a sealed container. 2SO2(g) + O2(g) 2SO3(g) The reaction is exothermic. Which cond
- June 2025, Paper 4 Higher, Q17(a) (1 mark): What does the symbol tell you about the reaction? [1]
- June 2025, Paper 4 Higher, Q17(b)(i) (1 mark): What is the catalyst used? Tick (✓) one box. Iron Manganese(IV) oxide Nickel Platinum [1]
- June 2024, Paper 2 Foundation, Q22(a)(i) (1 mark): State how you can tell that this reaction is reversible. [1]
- June 2024, Paper 2 Foundation, Q22(a)(ii) (1 mark): What is a closed system? [1]
- June 2024, Paper 2 Foundation, Q22(a)(iii) (2 marks): If dynamic equilibrium is reached, which of these statements are correct? Tick (✓) two boxes. Only ammonia, NH3, is being made. The amounts of reactants and pro
- June 2024, Paper 2 Foundation, Q22(b) (1 mark): The reaction in the Haber process can be reversed by altering the reaction conditions. The reaction can be reversed by altering the pressure. Suggest one other
- June 2024, Paper 4 Higher, Q12 (1 mark): The reaction between hydrogen, H2, and iodine, I2, is reversible. H2(g) + I2(g) 2HI(g) The reaction is exothermic. What will increase the yield of hydrogen iodi
- June 2024, Paper 4 Higher, Q17(a)(i) (1 mark): State how you can tell that this reaction is reversible. [1]
- June 2024, Paper 4 Higher, Q17(a)(ii) (1 mark): What is a closed system? [1]
- June 2024, Paper 4 Higher, Q17(a)(iii) (2 marks): If dynamic equilibrium is reached, which of these statements are correct? Tick (✓) two boxes. Only ammonia, NH3, is being made. The amounts of reactants and pro
- June 2024, Paper 4 Higher, Q17(b) (1 mark): The reaction in the Haber process can be reversed by altering the reaction conditions. The reaction can be reversed by altering the pressure. Suggest one other
- June 2023, Paper 2 Foundation, Q11 (1 mark): Ammonia is made in the Haber process. N2 + 3H2 2NH3 What happens when this reaction reaches equilibrium? A The backward reaction happens at a faster rate than t
- June 2023, Paper 4 Higher, Q13 (1 mark): Which graph shows a dynamic equilibrium? A Reaction rate Time (s) B Reaction rate Time (s) C Reaction rate Time (s) D Reaction rate Time (s) Your answer [1]
- June 2023, Paper 4 Higher, Q21(a)(i) (3 marks): Describe and explain the effect on the yield of methanol from using a pressure of 15 atmospheres. [3]
- June 2023, Paper 4 Higher, Q21(a)(ii) (1 mark): The yield of methanol is greater when a temperature of 150 °C is used instead of 250 °C. Suggest why a temperature of 150 °C is not used in industry. [1]
- June 2023, Paper 4 Higher, Q21(b) (1 mark): A catalyst is used to speed up the reaction. Describe the effect on the position of equilibrium from using a catalyst. [1]
- June 2022, Paper 2 Foundation, Q8 (1 mark): Which statement describes dynamic equilibrium? A Occurs in a closed system and the backward reaction is faster than the forward reaction. B Occurs in a closed s
- June 2022, Paper 4 Higher, Q21(a) (2 marks): State what is meant by a dynamic equilibrium. [2]
- June 2022, Paper 4 Higher, Q21(b)(i) (2 marks): The forward reaction is endothermic. The temperature of the equilibrium mixture is increased. State and explain what happens to the position of the equilibrium.
- June 2022, Paper 4 Higher, Q21(b)(ii) (1 mark): The highest yield of hydrogen gas is made using a low pressure, such as 1 atmosphere. The reaction is actually carried out using a catalyst at a pressure of 30
- November 2021, Paper 2 Foundation, Q18(a) (1 mark): What is meant by the symbol in the equation? [1]
- November 2021, Paper 2 Foundation, Q18(b)(i) (1 mark): What is the percentage of ammonia made at 350 °C and 200 atmospheres? Percentage of ammonia = % [1]
- November 2021, Paper 2 Foundation, Q18(b)(ii) (1 mark): What temperature and pressure, shown on Fig. 18.1, make the highest percentage of ammonia? Temperature = °C Pressure = atmospheres [1]
- November 2021, Paper 4 Higher, Q4 (1 mark): What are the conditions usually used for the production of ammonia in the Haber process? N2 + 3H2 2NH3 A 200 °C, 450 atmospheres pressure and an iron catalyst B
- November 2021, Paper 4 Higher, Q13 (1 mark): An alcohol and a carboxylic acid react to form an ester and water in an equilibrium reaction. alcohol + carboxylic acid ester + water Why is an acid catalyst us
- November 2021, Paper 4 Higher, Q22(b) (4 marks): The reaction to make hydrogen iodide is an equilibrium reaction. H2(g) + I2(g) 2HI(g) The forward reaction is exothermic. The yield of hydrogen iodide and the r
- November 2020, Paper 2 Foundation, Q3 (1 mark): Look at the equation for the Haber process. N2 + 3H2 2NH3 What is meant by the symbol in the equation? A A reaction that involves a catalyst. B A reaction that
- November 2020, Paper 4 Higher, Q9 (1 mark): The Contact process produces sulfur trioxide, SO3, in an exothermic reaction. 2SO2 + O2 2SO3 The temperature in the reaction vessel is usually 450 °C. What happ
- June 2019, Paper 2 Foundation, Q19(a)(i) (1 mark): What happens to the rate of the forward and backward reactions at dynamic equilibrium? [1]
- June 2019, Paper 2 Foundation, Q19(a)(ii) (1 mark): What happens to the concentrations of the reacting substances at equilibrium? [1]
- June 2019, Paper 4 Higher, Q7 (1 mark): Which statement describes what happens when a reaction reaches equilibrium? A The forward reaction happens at a faster rate than the backwards reaction. B The f
- June 2019, Paper 4 Higher, Q18(a) (2 marks): Write the balanced symbol equation for the reaction. [2]
- June 2019, Paper 4 Higher, Q18(b)(ii) (2 marks): The company thinks that the increase in temperature will increase the yield of ammonia. Is the company correct? Explain your answer. [2]
- June 2019, Paper 4 Higher, Q18(c) (2 marks): The company wants to reduce the cost of making the ammonia. They decide to reduce the pressure used to 150 atmospheres. Write about two disadvantages of using a
- June 2018, Paper 2 Foundation, Q9 (1 mark): Which statement is true for a reversible reaction when it is at dynamic equilibrium? A The concentration of the products is increasing. B The rate of the backwa
- June 2018, Paper 2 Foundation, Q19(a) (1 mark): The reaction between nitrogen and hydrogen is reversible. Explain what this means. [1]
- June 2018, Paper 2 Foundation, Q19(b)(i) (1 mark): Describe how the percentage of ammonia changes as the pressure increases at 450 °C. [1]
- June 2018, Paper 2 Foundation, Q19(b)(ii) (1 mark): Write down a temperature and pressure which make 20% of ammonia. Temperature = °C [1] Pressure = atmospheres
- June 2018, Paper 4 Higher, Q3 (1 mark): Which statement is true for a reversible reaction when it is at dynamic equilibrium? A The concentration of the products is increasing. B The rate of the backwa
- June 2018, Paper 4 Higher, Q7 (1 mark): Look at the equation for a reversible reaction. 4NO(g) + 6H2O(g) ∆H = –950 kJ mol–1 4NH3(g) + 5O2(g) The reversible reaction forms a dynamic equilibrium in a se
- June 2018, Paper 4 Higher, Q19 (6 marks): 19* Ethanol is manufactured by reacting ethene, C2H4, with steam. The reaction is reversible and occurs in a closed system. C2H5OH(g) ∆H = – 45 kJ mol–1 C2H4(g)
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