QCEVault

Chemical equilibrium — Question 26

QCAA 2021, Paper 1 · 5 marks

Q26 · 2021 · Paper 1Unclassified5 marks

QUESTION 26 (5 marks)

The graph represents changes in concentration over time for three gaseous molecules (X2, Y2 and XY) in a closed system at constant temperature and pressure.

Chemistry question figure

a) Identify whether XY is the reactant or the product.

[1 mark]

b) Calculate the equilibrium constant (Kc) value.

[2 marks]

Chemistry question figure

c) Determine whether the position of equilibrium favours the reactants or products. Explain your reasoning.

[2 marks]

Question linkQCAA assessment resources

Related questions

  1. Q7 · 2025 QCAA · Paper 1 · 1 mark
    QUESTION 7 Which of the following is exchanged with the surroundings when a chemical reaction reaches dynamic equilibrium? (A) gases (B) matter (C) energy (D) products
    Chemical equilibrium
  2. Q17 · 2025 QCAA · Paper 1 · 1 mark
    QUESTIONS 17–18 Questions 17–18 refer to the relationship between the concentration of nitrogen (N2), hydrogen (H2) and ammonia (NH3) in a closed system, as shown. N2(g) + 3H2(g)  2NH3(g) + heat NH3 Concentration (mol L−1) H2 N2 t1 Time (min)
    QUESTION 17 Determine the equilibrium law expression (Kc) for the reaction. [ ] 2 NH 3 (A) K = c [ ] [ ] N 3 H 2 2…
    Chemical equilibrium
  3. Q18 · 2025 QCAA · Paper 1 · 1 mark
    QUESTIONS 17–18 Questions 17–18 refer to the relationship between the concentration of nitrogen (N2), hydrogen (H2) and ammonia (NH3) in a closed system, as shown. N2(g) + 3H2(g)  2NH3(g) + heat NH3 Concentration (mol L−1) H2 N2 t1 Time (min)
    QUESTION 18 Determine the change applied to the system at t1. (A) N2(g) was added. (B) Pressure was increased. (C…
    Chemical equilibrium
  4. Q19 · 2025 QCAA · Paper 1 · 1 mark
    QUESTIONS 19–20 Questions 19–20 refer to the reversible chemical reaction and enthalpy level diagram shown. 2AB2(g) + B2(g)  2AB3(g) 100 80 Energy (kJ mol−1) 60 40 20 0 Progress of forward reaction QUESTION 19 Which statement is true for the forward reaction? (A) Energy is a product. (B) The reaction is endothermic. (C) Enthalpy change (ΔH) is positive.…
    Chemical equilibrium