Chemical equilibria: reversible reactions, dynamic equilibrium: past paper questions
Real questions on chemical equilibria: reversible reactions, dynamic equilibrium
The newest 20 of 212 written questions. Open one to see it on the real paper.
- 9701/41 · May/June 2026 · Q9b(i)[1]
Explain what is meant by isoelectric point.
See it on the paper → - 9701/41 · May/June 2026 · Q9b(ii)[3]
Complete Table 9.2 to show the predominant species formed by amino acids T and U at the pH values shown. Table 9.2 pH 4.0 pH 5.5 pH 8.0 T U
See it on the paper → - 9701/21 · October/November 2025 · Q1d(i)[1]
State what is meant by dynamic equilibrium.
See it on the paper → - 9701/21 · October/November 2025 · Q1d(ii)[1]
Identify the condition necessary to establish dynamic equilibrium.
See it on the paper → - 9701/21 · October/November 2025 · Q1d(iii)[4]
CrO 42– (aq) ions are yellow and Cr 2 O 72– (aq) ions are orange. State what is observed when the following changes are made to an equilibrium mixture of acidified CrO 42– (aq) and Cr 2 O 72– (aq) ions. • The equilibrium mixture is warmed gently. observation explanation • Dilute HCl (aq) is added to the equilibrium mix...
See it on the paper → - 9701/22 · October/November 2025 · Q2e(i)[1]
State what is meant by dynamic equilibrium.
See it on the paper → - 9701/22 · October/November 2025 · Q2e(ii)[1]
Identify the condition necessary to establish dynamic equilibrium.
See it on the paper → - 9701/22 · October/November 2025 · Q2e(iii)[4]
S 2 Cl 2 (l) is yellow and SCl 2 (l) is red. S 2 Cl 2 (l) + Cl 2 (g) 2SCl 2 (l) ΔH = – 41 kJ mol –1 State what is observed when the following changes are made to an equilibrium mixture of S 2 Cl 2 (l) and SCl 2 (l). Explain your answers. • The equilibrium mixture is warmed gently. observation explanation • The overall...
See it on the paper → - 9701/23 · October/November 2025 · Q1d(i)[1]
State what is meant by dynamic equilibrium.
See it on the paper → - 9701/23 · October/November 2025 · Q1d(ii)[1]
Identify the condition necessary to establish dynamic equilibrium.
See it on the paper → - 9701/41 · October/November 2025 · Q1e(i)[2]
Write the expression for the solubility product, K sp , of Hg 2 F 2 . Include the units. K sp =
See it on the paper → - 9701/41 · October/November 2025 · Q1e(ii)[1]
The solubility of Hg 2 F 2 is 9.20 × 10 –3 mol dm –3 at 298 K. Calculate the value of K sp of Hg 2 F 2 at 298 K. K sp =
See it on the paper → - 9701/42 · October/November 2025 · Q3b(iv)[3]
Table 3.1 shows three possible values of the K a of dimethylpropanoic acid, (CH 3 ) 3 CCOOH. Place a tick in Table 3.1 to show the correct value. Explain your answer. Table 3.1 value of K a / mol dm –3 place one tick (✓) in this column 9.33 × 10 –6 1.35 × 10 –5 3.35 × 10 –5 explanation
See it on the paper → - 9701/43 · October/November 2025 · Q8d(i)[1]
Name the mechanism of this reaction.
See it on the paper → - 9701/52 · October/November 2025 · Q1c(ii)[1]
Suggest why flask A is left to stand for twelve hours in step 4.
See it on the paper → - 9701/52 · October/November 2025 · Q1d(i)[1]
State if concordant titres have been achieved. Explain your answer.
See it on the paper → - 9701/52 · October/November 2025 · Q1d(ii)[1]
Calculate the percentage error in the titre volume in titration 2. Show your working. percentage error = (ii)
See it on the paper → - 9701/52 · October/November 2025 · Q1d(iii)[1]
The student repeats the experiment using KSCN(aq) at a higher concentration. The student obtains smaller titres. Suggest one reason why a larger titre is better than a smaller titre. (iii)
See it on the paper → - 9701/52 · October/November 2025 · Q1e(i)[1]
Calculate [Ag + (aq)] in the equilibrium mixture in flask A. [Ag + (aq)] eqm = mol dm –3
See it on the paper → - 9701/52 · October/November 2025 · Q1e(ii)[1]
Calculate [Fe 3+ (aq)] in the equilibrium mixture in flask A. [Fe 3+ (aq)] eqm = mol dm –3
See it on the paper →
What examiners said
There were many good answers here. Many candidates wrote about increasing the concentration of reactants, ignoring the state of PCl 3. Answers giving general definitions of equilibrium were ignored.
— Examiner report, February/March 2025, 9701/22 Q1(a)(ii) (Cambridge)
Well-rehearsed arguments related the significance of increasing temperature on the position of equilibrium to the example given. More able candidates showed no ambiguity and made explicit reference to the effect of an increase in temperature on the position of this equilibrium in terms of either the ‘forward reaction is exothermic’ or ‘the reverse reaction is endothermic’. Less precise answers inc...
— Examiner report, October/November 2023, 9701/22 Q2(b) (Cambridge)
This question proved to be demanding. A few candidates found Kp using an appropriate method; they worked out the mole fraction of the components, converted them into partial pressures and then substituted these values into the correct expression for Kp. Weaker candidates calculated Kp directly from moles and included moles in the units. Deduction of units also presented difficulties. Many answers...
— Examiner report, October/November 2023, 9701/22 Q2(c) (Cambridge)
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