plumiBrønsted–Lowry acids and bases: OCR A‑Level Chemistry A questions
OCR A-Level Chemistry A past-paper questions on 5.1.3.1 Brønsted–Lowry acids and bases, 2016–2025, with mark schemes and examiner’s reports where available.
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Q4(a)(i)
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Open the full PDFYour answerQ5(b)(ii)
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All 9 questions on Brønsted–Lowry acids and bases, as a list
- June 2024, Paper 3, Q4(a)(i) (2 marks): During the equilibria, H2PO4 Explain this statement, using the equilibria 1, 2 and 3, as required. [2]
- June 2023, Paper 1, Q20(e)(i) (1 mark): Explain what is meant by the term monobasic acid. [1]
- June 2022, Paper 1, Q12 (1 mark): Ammonia and water react to set up an acid–base equilibrium. What are the Brønsted–Lowry acids in the equilibrium mixture? H2O and OH– A OH– and NH3 B + and H2O
- November 2021, Paper 3, Q5(b)(ii) (2 marks): When added to water, hydrazoic acid forms an equilibrium mixture containing conjugate acid–base pairs. Complete the equation for this equilibrium and label the
- November 2020, Paper 1, Q18(b) (2 marks): The Ka values of HCOOH and CH3COOH are shown in Table 18.1. Ka / mol dm−3 Weak acid 1.82 × 10−4 HCOOH 1.78 × 10−5 CH3COOH Table 18.1 A student adds methanoic ac
- June 2019, Paper 1, Q12 (1 mark): The equation shows the dissociation of the acid H3AsO4 in water. – + H3O+ H3AsO4 + H2O H2AsO4 Which pair is a conjugate acid–base pair? A H3AsO4 and H2O − and H
- June 2019, Paper 3, Q2(a) (1 mark): In Step 1, sodium carbonate, Na2CO3, makes the reaction mixture alkaline. Write an ionic equation to show how carbonate ions form an alkaline solution in water.
- June 2018, Paper 3, Q6(a)(iii) (3 marks): Reaction 6.1 takes place in two steps. OH– ions act as a catalyst. In step 1, ethanal reacts with OH– ions to set up an acid–base equilibrium. In step 2, compou
- June 2017, Paper 1, Q21(b) (2 marks): Ethanoic acid is added to another weak acid, fluoroethanoic acid, FCH2COOH (Ka = 2.19 × 10–3 mol dm–3). An equilibrium is set up containing two acid-base pairs.
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