Brønsted–Lowry theory of acids and bases: past paper questions

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• Question 13May/June 2026, paper 11Multiple choice1 markHas a diagram

  Which pH titration curve shows the result of a titration of a strong alkali with a weak acid?

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• Question 13Oct/Nov 2025, paper 11Multiple choice1 markHas a diagram

  Aqueous acid P and aqueous alkali Q have the same concentration. $20{\text{ cm}}^3$ of P is added to a conical flask. Q is slowly added to the flask and the volume of Q and the pH are recorded.

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• Question 24Oct/Nov 2024, paper 11Multiple choice1 mark

  Three statements about ammonia molecules and ammonium ions are given. 1 In aqueous solution, ammonia molecules form coordinate bonds with hydroxide ions. 2 Ammonium ions are Brønsted–Lowry acids.

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• Question 26Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  $\text{NaOH(aq)}$ is added to ${\text{NH}}_4\text{Cl(aq)}$. The mixture is warmed. The gas that is produced turns damp red litmus paper blue.

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• Question 14May/June 2026, paper 12Multiple choice1 mark

  Ethanoic acid dissociates in water. $${\text{CH}}_3\text{COOH}+{\text{H}}_2\text{O}\rightleftharpoons {\text{CH}}_3{\text{COO}}^{-}+{\text{H}}_3{\text{O}}^{+}\mathrm{\Delta }H=-2{\text{ kJ mol}}^{-1}$$ Which change causes the pH of this aqueous solution to decrease?

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• Question 23Oct/Nov 2025, paper 11Multiple choice1 mark

  Which statement is correct?

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• Question 16May/June 2023, paper 13Multiple choice1 markHas a diagram

  Solutions X and Y both have a concentration of $0.10{\text{ mol dm}}^{-3}$. A fixed volume of solution X is added to a conical flask, and solution Y is added from a burette to the conical flask. A titration is performed.

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• Question 24May/June 2026, paper 13Multiple choice1 mark

  Ammonium sulfate is heated with calcium hydroxide. Two statements about the reaction are listed. 1 The ammonium ion acts as a base during the reaction.

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• Question 22May/June 2024, paper 12Multiple choice1 mark

  Which statement describes a property of an ammonium ion?

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• Question 3May/June 2026, paper 22Structured8 marks

  Separate samples of $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$ and $\mathrm{N}\mathrm{a}\mathrm{B}\mathrm{r}$ are reacted with concentrated ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$. Table 3.1 shows the observations for each reaction. Write an equation for reaction 1.

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• Question 9May/June 2025, paper 11Multiple choice1 markHas a diagram

  An aqueous solution X contains substance HQ which behaves as a weak acid.

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• Question 23May/June 2024, paper 13Multiple choice1 mark

  $\mathrm{N}{\mathrm{H}}_4\mathrm{C}\mathrm{l}$ reacts with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$ in an aqueous solution. Which statement is correct?

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• Question 16May/June 2025, paper 11Multiple choice1 mark

  A reaction involving ammonium ions is shown. $${\text{NH}}_4^{+}+{\text{OH}}^{-}\rightleftharpoons {\text{NH}}_3+{\text{H}}_2\text{O}$$ Four statements about this reaction are listed. 1 The ammonium ions are reduced.

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• Question 4May/June 2024, paper 23Structured16 marksHas a diagram

  $\mathrm{N}{\mathrm{H}}_3(\mathrm{g})$ reacts with $\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{g})$ to produce $\mathrm{N}{\mathrm{H}}_4\mathrm{C}\mathrm{l}(\mathrm{s})$, as shown. $$\mathrm{N}{\mathrm{H}}_3(\mathrm{g})+\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{g})\to \mathrm{N}{\mathrm{H}}_4\mathrm{C}\mathrm{l}(\mathrm{s})$$ Draw a diagram to show the ionic, covalent and coordinate bonding present in a formula unit of $\mathrm{N}{\mathrm{H}}_4\mathrm{C}\mathrm{l}$.

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• Question 3May/June 2025, paper 13Multiple choice1 markHas a diagram

  The equation shows the overall reaction between an amine and an acid chloride.

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• Question 2May/June 2025, paper 23Structured8 marks

  The chemical properties of oxides are related to the chemical bonding present in these compounds. A Period 3 oxide produces a solution with a pH greater than 10 when it is added to water. State the formula of the oxide.

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