Skip to content
Try on iPad

Equilibria (acid–base): OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on PL Equilibria (acid–base) (specification points PL(h)–(j)), 2016–2025, with its mark scheme and examiner’s report.

Find questions2,049
Calculations

2,049 questions

  1. Q25

    June 2025 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2025 Paper 1, question 25: At a certain pH, the amino acid glycine exists as: NH2CH2COO– What is correct about this structure? A It exists at acid pHs. B It is a zwitterion. C It is the c

  2. Q6

    June 2024 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2024 Paper 1, question 6: Which species is present in an acidic solution of glycine, H2NCH2COOH? H3N+CH2COOH A H3N+CH2COO– B H2NCH2COO– C + D H2NCH2COOH2 Your answer [1]

  3. Q35(d)(i)

    June 2023 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2023 Paper 1, question 35(d)(i): The formula of the species present in the aqueous solution of alanine is H3N+CH(CH3)COO–. Name this type of species. [1]

  4. Q35(d)(ii)

    June 2023 · Paper 1

    2 marksPL Equilibria (acid–base)
    Mark scheme (PDF)
    The whole paper ↗
    June 2023 Paper 1, question 35(d)(ii): Write equations for the reactions that occur in the two beakers. Equation for reaction with acid (H3O+). Equation for reaction with alkali (OH–). [2]

  5. Q4(a)(ii)

    June 2022 · Paper 2

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2022 Paper 2, question 4(a)(ii): Glycine HOOCCH2NH2 is another amino acid. In solution, glycine exists as a zwitterion. Draw the structure of this zwitterion. [1]

  6. Q1(b)

    June 2022 · Paper 3

    2 marksPL Equilibria (acid–base)
    The whole paper ↗
    June 2022 Paper 3, question 1(b): Compound B behaves as a base. Complete the diagram of a mechanism that shows how a molecule of compound B reacts with water to give a basic solution. Show ‘curl

  7. Q4(e)

    November 2021 · Paper 3

    2 marksPL Equilibria (acid–base)
    The whole paper ↗
    November 2021 Paper 3, question 4(e): Buffer solutions can also be prepared using weak bases in solution such as amines, RNH2. Explain, in terms of their electronic structure, why amines behave as b

  8. Q1(b)(ii)

    November 2020 · Paper 2

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    November 2020 Paper 2, question 1(b)(ii): Phenylalanine in solution exists mainly as a zwitterion. Complete the diagram in Fig. 1.3 to show the structure of this zwitterion. Ph Fig. 1.3 [1]

  9. Q30

    June 2019 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2019 Paper 1, question 30: Which statement(s) is/are correct about amino acids? 1 They all have a chiral centre. 2 They form buffer solutions in aqueous solution. 3 They form crystalline

  10. Q20

    June 2018 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2018 Paper 1, question 20: Which statement is not correct about amines? A The lone pair on the nitrogen allows them to act as nucleophiles. B They react with carboxylic acids to form amid

  11. Q28

    June 2018 · Paper 1

    1 markPL Equilibria (acid–base)
    The whole paper ↗
    June 2018 Paper 1, question 28: Which statement/s is/are correct about solutions of amino acids with the general formula RCH(NH2)COOH? 1 They contain zwitterions. 2 They react with sodium hydr

  12. Q1(a)(i)

    June 2017 · Paper 2

    2 marksPL Equilibria (acid–base)
    The whole paper ↗
    June 2017 Paper 2, question 1(a)(i): Write an equation for this reaction. [2]

  13. Q1(b)(ii)

    June 2017 · Paper 3

    2 marksPL Equilibria (acid–base)
    The whole paper ↗
    June 2017 Paper 3, question 1(b)(ii): Functional group 2 and functional group 3 are hydrolysed under the acid conditions to give three products. The products are methanol, and ions formed by the ami

  14. Q1(b)(iii)

    June 2017 · Paper 3

    2 marksPL Equilibria (acid–base)
    The whole paper ↗
    June 2017 Paper 3, question 1(b)(iii): Amino acids such as phenylalanine exist as zwitterions. Use the structure of phenylalanine to help explain how amino acids form zwitterions. Draw the structure
All 14 questions on Equilibria (acid–base), as a list
  1. June 2025, Paper 1, Q25 (1 mark): At a certain pH, the amino acid glycine exists as: NH2CH2COO– What is correct about this structure? A It exists at acid pHs. B It is a zwitterion. C It is the c
  2. June 2024, Paper 1, Q6 (1 mark): Which species is present in an acidic solution of glycine, H2NCH2COOH? H3N+CH2COOH A H3N+CH2COO– B H2NCH2COO– C + D H2NCH2COOH2 Your answer [1]
  3. June 2023, Paper 1, Q35(d)(i) (1 mark): The formula of the species present in the aqueous solution of alanine is H3N+CH(CH3)COO–. Name this type of species. [1]
  4. June 2023, Paper 1, Q35(d)(ii) (2 marks): Write equations for the reactions that occur in the two beakers. Equation for reaction with acid (H3O+). Equation for reaction with alkali (OH–). [2]
  5. June 2022, Paper 2, Q4(a)(ii) (1 mark): Glycine HOOCCH2NH2 is another amino acid. In solution, glycine exists as a zwitterion. Draw the structure of this zwitterion. [1]
  6. June 2022, Paper 3, Q1(b) (2 marks): Compound B behaves as a base. Complete the diagram of a mechanism that shows how a molecule of compound B reacts with water to give a basic solution. Show ‘curl
  7. November 2021, Paper 3, Q4(e) (2 marks): Buffer solutions can also be prepared using weak bases in solution such as amines, RNH2. Explain, in terms of their electronic structure, why amines behave as b
  8. November 2020, Paper 2, Q1(b)(ii) (1 mark): Phenylalanine in solution exists mainly as a zwitterion. Complete the diagram in Fig. 1.3 to show the structure of this zwitterion. Ph Fig. 1.3 [1]
  9. June 2019, Paper 1, Q30 (1 mark): Which statement(s) is/are correct about amino acids? 1 They all have a chiral centre. 2 They form buffer solutions in aqueous solution. 3 They form crystalline
  10. June 2018, Paper 1, Q20 (1 mark): Which statement is not correct about amines? A The lone pair on the nitrogen allows them to act as nucleophiles. B They react with carboxylic acids to form amid
  11. June 2018, Paper 1, Q28 (1 mark): Which statement/s is/are correct about solutions of amino acids with the general formula RCH(NH2)COOH? 1 They contain zwitterions. 2 They react with sodium hydr
  12. June 2017, Paper 2, Q1(a)(i) (2 marks): Write an equation for this reaction. [2]
  13. June 2017, Paper 3, Q1(b)(ii) (2 marks): Functional group 2 and functional group 3 are hydrolysed under the acid conditions to give three products. The products are methanol, and ions formed by the ami
  14. June 2017, Paper 3, Q1(b)(iii) (2 marks): Amino acids such as phenylalanine exist as zwitterions. Use the structure of phenylalanine to help explain how amino acids form zwitterions. Draw the structure

Questions, mark schemes and examiner’s reports are © OCR, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Every OCR A-Level Chemistry B paper.

Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.