plumiEquilibria: Edexcel International A Level Chemistry questions
Every Edexcel International A Level Chemistry exam question on 9B Equilibria (specification points 9.9–9.11), 2019–2025, with its mark scheme and examiner’s report.
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Q11(a)
The whole paper ↗Your answerQ11(b)
The whole paper ↗Your answerQ17(c)(ii)
The whole paper ↗Q21(e)(iii)
The whole paper ↗Q2(a)
The whole paper ↗Your answerQ2(b)
The whole paper ↗Your answerQ19(b)(ii)
The whole paper ↗Q19(b)
The whole paper ↗Q19(c)(i)
The whole paper ↗Q19(c)(ii)
The whole paper ↗Q19(c)(iv)
The whole paper ↗Q19(c)(v)
The whole paper ↗Q3(a)(i)
The whole paper ↗Q3(b)
The whole paper ↗Q19(a)(i)
The whole paper ↗Q19(a)(ii)
The whole paper ↗- Your answer
Q11(a)
The whole paper ↗Your answerQ11(b)
The whole paper ↗Your answer- Your answer
All 43 questions on Equilibria, as a list
- June 2025, AS Unit 2, Q11(a) (1 mark): Which of the following statements must be correct? (1) A the reactions stop B the sum of the masses of sulfur(IV) oxide and oxygen is equal to the mass of sulf
- June 2025, AS Unit 2, Q11(b) (1 mark): How does the use of a catalyst affect the equilibrium? (1) A only the rate of the forward reaction increases B the position of equilibrium moves to the right C
- June 2025, AS Unit 2, Q17(c)(ii) (4 marks): Methanol can be produced from the captured carbon dioxide by reaction with hydrogen using a copper catalyst. The equation for the reaction is shown. CO2(g) + 3H
- January 2025, AS Unit 2, Q21(e)(iii) (5 marks): A one‑step process is being developed. This is carried out at 101 kPa and 800 °C. CH4 + ½O2 CH3OH ΔH = –164.3 kJ mol–1 Deduce how the reaction conditions coul
- October 2024, AS Unit 2, Q2(a) (1 mark): What would be the effect of lowering the temperature? (1) A rate increases, yield increases B rate increases, yield decreases C rate decreases, yield increases
- October 2024, AS Unit 2, Q2(b) (1 mark): What would be the effect of increasing the pressure? (1) A rate increases, yield increases B rate increases, yield decreases C rate decreases, yield increases D
- October 2024, AS Unit 2, Q19(b)(ii) (2 marks): State and explain what happens to the position of equilibrium when sodium hydroxide solution, NaOH(aq), is added to this equilibrium mixture. (2)
- June 2024, AS Unit 2, Q19(b) (2 marks): Under these conditions, the conversion of ethene to ethanol is 5 % at equilibrium but the overall yield of ethanol for the process is 95 %. Suggest what happens
- June 2024, AS Unit 2, Q19(c)(i) (2 marks): Explain why the temperature used is a compromise. (2)
- June 2024, AS Unit 2, Q19(c)(ii) (2 marks): Explain why a manufacturer might suggest a pressure of greater than the compromise pressure of 7 MPa. (2)
- June 2024, AS Unit 2, Q19(c)(iv) (1 mark): Give one other reason for not operating the process at a pressure greater than 7 MPa. Do not include safety considerations in your answer. (1)
- June 2024, AS Unit 2, Q19(c)(v) (2 marks): Increasing the amount of water in the reaction mixture, without changing the pressure, might also be suggested. Suggest one advantage and one disadvantage of in
- June 2024, AS Unit 3, Q3(a)(i) (3 marks): Explain the observations you would make as the amount of chlorine gas in the U‑tube increases. (3)
- June 2024, AS Unit 3, Q3(b) (2 marks): Explain what you could do to the U‑tube to result in more brown liquid being observed. (2)
- June 2024 (R), AS Unit 2, Q19(a)(i) (2 marks): Explain what you would see on heating the mixture. (2)
- June 2024 (R), AS Unit 2, Q19(a)(ii) (2 marks): Explain what you would see on increasing the pressure. (2)
- January 2024, AS Unit 2, Q14 (1 mark): Which statement is not true for a system at dynamic equilibrium? A the position of equilibrium is affected by temperature, by pressure and by catalysts B the c
- October 2023, AS Unit 2, Q11(a) (1 mark): What is the effect of a decrease in temperature? (1) A rate increases and yield decreases B rate increases and yield increases C rate decreases and yield decrea
- October 2023, AS Unit 2, Q11(b) (1 mark): What is the effect of an increase in pressure? (1) A rate increases and yield decreases B rate increases and yield increases C rate decreases and yield decrease
- October 2023, AS Unit 2, Q12 (1 mark): A mixture of 1.0 cm3 of 0.20 mol dm–3 potassium chromate(VI) and 5.0 cm3 of 1.0 mol dm–3 sulfuric acid forms the equilibrium shown. 2–(aq) + 2H+(aq) Cr2O7 2–(
- October 2023, AS Unit 2, Q20(c) (3 marks): Between 1960 and 2020 the amount of carbon dioxide in the atmosphere rose from 320 parts per million (ppm) to 420 ppm. The recent rapid increase in the atmosphe
- June 2023, AS Unit 3, Q4(d) (2 marks): Dissolving calcium hydroxide in water is an exothermic process. Describe what you would see if the saturated solution of calcium hydroxide was heated from room
- January 2023, AS Unit 2, Q22(a)(i) (1 mark): Give the reason why excess steam is used in the first reaction. (1)
- January 2023, AS Unit 2, Q22(a)(ii) (1 mark): Predict which of T1 and T2 is the higher temperature. Justify your answer. (1)
- January 2023, AS Unit 2, Q22(b)(i) (1 mark): Suggest one reason why CO2 is removed. (1)
- January 2023, AS Unit 2, Q22(c) (2 marks): In Stage 2, the hydrogen from Stage 1 reacts with nitrogen (from the air) to produce ammonia. The conditions for this reaction are: • a temperature of 700 K • a
- January 2023, AS Unit 2, Q22(f) (2 marks): The NO from the first reaction in Stage 3 is cooled and then converted to nitrogen dioxide, NO2 , by reaction with more O2 . 2NO(g) + O2(g) 2NO2(g) Nitric aci
- January 2023, AS Unit 2, Q22(h) (2 marks): Suggest two reasons why it is more profitable to carry out all four stages at the same site, instead of using different sites for each stage in the industrial p
- October 2022, AS Unit 2, Q21(a)(ii) (4 marks): Step 2 is a reversible reaction. 2SO2(g) + O2(g) 2SO3(g) ∆H = −196 kJ mol−1 State the effect on the position of equilibrium when the temperature and pressure
- June 2022, AS Unit 2, Q11 (1 mark): A mixture of hydrogen and iodine is left in a sealed container at 300 °C until equilibrium is established. H2(g) + I2(g) 2HI(g) The equilibrium mixture is the
- June 2022, AS Unit 2, Q18(d) (2 marks): Ethanol can be manufactured by reacting ethene with steam. C2H4(g) + H2O(g) C2H5OH(g) ΔrH = −45 kJ mol−1 This reaction is usually carried out in industry at 3
- January 2022, AS Unit 2, Q18 (1 mark): Which conditions give the highest yield for the forward reaction? NH4Cl(s) NH3(g) + HCl(g) ΔH = +176 kJ mol−1 A high temperature, high pressure B high tempera
- January 2022, AS Unit 2, Q19 (1 mark): Nitrogen dioxide and dinitrogen tetroxide exist in equilibrium. 2NO2(g) N2O4(g) brown gas colourless gas When an equilibrium is set up in a gas syringe, the m
- January 2022, AS Unit 2, Q24(e)(i) (1 mark): Complete the equation for this reversible reaction. State symbols are not required. (1) (NH2)2CO + H2O
- October 2021, AS Unit 2, Q22(e)(i) (6 marks): Typical conditions are 300 °C and 60 atm with a catalyst of phosphoric acid. Explain why these conditions are used, by describing the effect of changing the tem
- October 2021, AS Unit 2, Q22(f)(ii) (2 marks): Under these conditions, only about 5 % of the ethene is converted into ethanol as it passes over the catalyst. Suggest how the overall yield of this process can
- June 2021, AS Unit 2, Q22(b)(i) (4 marks): State and explain how the reaction conditions could be changed to maximise the equilibrium yield of phosgene in this reaction. (4)
- January 2021, AS Unit 2, Q19(a) (6 marks): Explain the chemical reasons for the conditions used and why such a low initial yield is acceptable in the industrial process. (6)
- October 2020, AS Unit 2, Q17(a)(i) (2 marks): Explain why high pressure is used. (2)
- October 2020, AS Unit 2, Q17(a)(ii) (3 marks): Discuss the factors leading to a choice of 250 °C in this process. (3)
- January 2020, AS Unit 2, Q18(c)(iii) (2 marks): Explain the effect of increasing the pressure on the equilibrium yield of ammonia. (2)
- June 2019, AS Unit 2, Q3 (1 mark): A large amount of P is added to a small amount of Q. A reversible reaction occurs in which P reacts to form Q. P U Q Which graph shows how the concentrations of
- June 2019, AS Unit 2, Q4 (1 mark): Which equilibrium shifts to the right-hand side when the pressure in the system decreases at constant temperature? A N2(g) + 3H2(g) U 2NH3(g) B F2(g) + H2(g) U
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