plumiKc and Kp: expressions and calculations: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 13.1.1 Kc and Kp: expressions and calculations, 2019–2025, with mark schemes and examiner’s reports where available.
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Q13(a)
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All 43 questions on Kc and Kp: expressions and calculations, as a list
- June 2025, Unit 4, Q13(a) (1 mark): Which is the expression for the equilibrium constant, Kp? (1) 2 p SO 3 A Kp = 2 p SO p O 2 2 2 SO 3 B Kp = 2 SO O 2 2 2 p SO 3 C Kp = 2 p SO p O 2 2 2 p SO p
- June 2025, Unit 4, Q14(b)(i) (1 mark): Write the expression for the equilibrium constant Kc . (1)
- June 2025, Unit 4, Q14(b)(ii) (2 marks): Complete the table using the equilibrium equation and the data. (2) Substance NOCl NO Cl2 Initial mol 0.250 0 0 Equilibrium mol 0.016 Concentration / mol dm3
- June 2025, Unit 4, Q14(b)(iii) (3 marks): Using your answers from (b)(i) and (b)(ii), calculate the equilibrium constant, Kc . Give your answer to an appropriate number of significant figures and includ
- June 2025, Unit 6, Q2(d) (2 marks): From the results of the experiment, the student determined the concentration of the saturated solution of calcium hydroxide to be 0.0190 mol dm–3. Calculate the
- January 2025, Unit 4, Q5(a) (1 mark): What is the numerical value of Kp at 25°C using Equation 2? (1) A 2.0 × 1012 B 2.0 × 1022 C 2.0 × 1024 D 4.0 × 1024
- January 2025, Unit 4, Q5(b) (1 mark): The relationship between Kp and Kc is shown. K p K c Δ n R T where T is the temperature in kelvin, R is the gas constant 0.082 dm3 atm mol–1 K–1 and ∆n = moles
- October 2024, Unit 4, Q9 (1 mark): Magnesium nitrate decomposes on heating as shown. Mg(NO3)2(s) MgO(s) + 2NO2(g) + ½O2(g) What is the expression for the equilibrium constant, Kp , for this rea
- June 2024, Unit 4, Q4(a) (1 mark): 10 mol of N2(g) is heated with 30 mol of H2(g) in a sealed container. At equilibrium, 8.0 mol of NH3(g) is present. What is the total amount of gas, in mol, in
- June 2024, Unit 4, Q4(b) (1 mark): What is the expression for the equilibrium constant, Kp , for this reaction? (1) p ( N ) + p ( H ) 3 A 2 2 2 p ( NH ) 3 p ( NH ) 2 B 3 + 3 p ( N ) p ( H ) 2 2 p
- January 2024, Unit 4, Q1(b) (1 mark): What are the units of the equilibrium constant, Kp, for this reaction? (1) A atm B atm–1 C atm4 D atm–4
- January 2024, Unit 4, Q19(a)(i) (4 marks): Calculate the value for Kc for this equilibrium at 25 °C. Give your answer to an appropriate number of significant figures. (4)
- October 2023, Unit 4, Q6 (1 mark): Heating copper(II) nitrate results in the equilibrium shown. 2Cu(NO3)2(s) 2CuO(s) + 4NO2(g) + O2(g) Which is the expression for Kp? × × A Kp = 2( CuO) p 4( NO
- October 2023, Unit 4, Q15(a)(i) (3 marks): Calculate the number of moles of each substance at equilibrium. (3)
- October 2023, Unit 4, Q15(a)(ii) (4 marks): Calculate the value of Kc under these conditions. Include units in your answer. (4)
- June 2023, Unit 4, Q1 (1 mark): A homogeneous equilibrium is shown. W + X 2Y + Z What is the Kc expression for this equilibrium? A Kc = 2 Y Z W X 2 B Kc = Y Z W X C Kc = W X 2 Y Z D Kc = W X
- June 2023, Unit 4, Q2 (1 mark): The reaction shown occurs at 360 °C and 1 atm. CO + H2O CO2 + H2 ΔH = –41.2 kJ mol–1 What is the type of equilibrium and how is Kc affected by an increase in
- June 2023, Unit 4, Q3 (1 mark): What are the units of Kp for the equilibrium shown? N2(g) + 3H2(g) 2NH3(g) A atm–1 B atm C atm–2 D atm2
- January 2023, Unit 4, Q9(a) (1 mark): What is the equilibrium constant expression for this reaction? (1) × 4 A Kc = [ Fe O ] [ H ] 3 4 2 [ Fe] 3 × [ H O ] 4 2 × 4 B Kc = [ Fe O ] [ H ] 3 4 2 [ H O ]
- January 2023, Unit 4, Q20(b)(i) (1 mark): Give the expression for the equilibrium constant, Kp, for this reaction. (1)
- January 2023, Unit 4, Q20(b)(ii) (5 marks): Calculate the value of Kp, including units if required. (5)
- October 2022, Unit 4, Q6(c) (1 mark): What are the units of the equilibrium constant, Kp , for this reaction? (1) A atm−1 B atm C dm3 mol−1 D mol dm−3 Use this space for any rough working. Anything
- October 2022, Unit 4, Q18(a) (1 mark): Write the expression for the equilibrium constant, Kc , of this system. (1)
- October 2022, Unit 4, Q18(b) (4 marks): Chemist A carried out an experiment to determine Kc . 0.00500 mol of H2 and 0.0100 mol of I2 were heated in a sealed container of volume 1.00 dm3 . At equilibri
- June 2022, Unit 4, Q16(a)(i) (1 mark): Write the expression for the equilibrium constant, Kp . (1)
- June 2022, Unit 4, Q16(a)(ii) (3 marks): An equilibrium was established by mixing nitrogen and hydrogen in a 1 : 3 ratio by volume, at a temperature of 450 °C and pressure of 200 atm. The equilibrium m
- June 2022, Unit 4, Q16(a)(iii) (3 marks): Calculate the equilibrium constant. Give your answer to an appropriate number of significant figures and include units, if required. (3)
- January 2022, Unit 4, Q3(b) (1 mark): At 680 °C and 1 atm, 52.6 % of the molecules in the gas mixture are carbon monoxide. What is the partial pressure of carbon dioxide, in atmospheres? (1) A 0.237
- January 2022, Unit 4, Q4 (1 mark): The equation for the precipitation of lead(II) chloride is shown. Pb2+(aq) + 2Cl–(aq) PbCl2(s) What are the units of the equilibrium constant, Kc? A dm9 mol–3
- January 2022, Unit 4, Q21(a)(i) (4 marks): Calculate the value of the equilibrium constant, Kc, for this reaction at 25 °C. (4)
- October 2021, Unit 4, Q6(a) (1 mark): What is the equilibrium constant, Kc , for this reaction? (1) B Kc = [ CO H ][ ] 2 A Kc = [CO][H2] [ ] C C Kc = [ CO H ][ ] D Kc = [ CO H ][ ] 2 2 [ H O ] [ H O
- October 2021, Unit 4, Q19(a)(i) (1 mark): Give the expression for the equilibrium constant, Kp , for the reaction. (1)
- October 2021, Unit 4, Q19(a)(ii) (5 marks): Calculate the equilibrium constant, Kp , for the hydration of ethene at 150 °C. Include units with your answer. (5)
- June 2021, Unit 4, Q20(b)(i) (3 marks): Complete the table. (3) Initial amount Equilibrium amount Mole fraction Substance / mol / mol at equilibrium HCl 0.850 O2 0.600 H2O 0 Cl2 0 0.250 0.189 Total mo
- June 2021, Unit 4, Q20(b)(ii) (1 mark): Write the expression for the equilibrium constant, Kp . (1)
- June 2021, Unit 4, Q20(b)(iii) (3 marks): Use your answers to (b)(i) and (b)(ii) to calculate the value for Kp . Give your answer to an appropriate number of significant figures, and include units. (3)
- January 2021, Unit 4, Q18(a)(iii) (1 mark): Write the expression for the equilibrium constant, Kp , for this equilibrium. State symbols are not required. (1)
- January 2021, Unit 4, Q18(a)(iv) (4 marks): A mixture of 2.00 mol of sulfur dioxide and 1.00 mol of oxygen is allowed to reach equilibrium at 5.00 atm pressure. 1.60 mol of sulfur trioxide is formed. Calc
- October 2020, Unit 4, Q7 (1 mark): The equation for the equilibrium decomposition of hydrogen iodide into hydrogen and iodine can be written in two ways. 2HI(g) H2(g) + I2(g) Equilibrium consta
- October 2020, Unit 4, Q19(b)(i) (1 mark): Write the expression for the equilibrium constant, Kp , for the reaction in the Haber Process. N2(g) + 3H2(g) 2NH3(g) (1)
- October 2020, Unit 4, Q19(b)(ii) (3 marks): A mixture of nitrogen, hydrogen and ammonia is at equilibrium at 255 atm and 700 K. The partial pressure of nitrogen is 25 atm and that of hydrogen is 150 atm.
- January 2020, Unit 4, Q13(a) (1 mark): In which flask(s) was the equilibrium approached from the right-hand side of the equation? (1) A flask 1 only B flask 4 only C flasks 1 and 4 only D flasks 2 an
- January 2020, Unit 4, Q13(b) (1 mark): Which of these statements explains why it is possible to titrate the reaction mixture directly to find the equilibrium concentrations? (1) A the equilibrium rea
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