plumiThe rate-determining step: OCR A‑Level Chemistry A questions
OCR A-Level Chemistry A past-paper questions on 5.1.1.4 The rate-determining step, 2016–2025, with mark schemes and examiner’s reports where available.
All papers
All years
Loading the question…
Open the full PDFYour answerQ3(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ20(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ16(b)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ21(a)(ii)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ4(c)(i)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDFQ17(a)
The whole paper ↗
Loading the start of the question…
Loading the question…
Open the full PDF
All 7 questions on The rate-determining step, as a list
- June 2025, Paper 1, Q9 (1 mark): Hydrogen reacts with iodine monochloride, ICl , as shown in the equation: H2 + 2ICl 2HCl + I2 The mechanism for the reaction is: H2 + ICl HCl + HI slow step HI
- June 2025, Paper 3, Q3(b) (6 marks): This question is about equilibrium and rates. (b)* A reaction takes place when aqueous solutions of propanone, CH3COCH3(aq), and bromine, Br2(aq), are mixed in
- June 2024, Paper 1, Q20(b) (2 marks): Fluorine, F2, reacts with nitrogen dioxide, NO2, to form nitryl fluoride, NO2F, as shown in Reaction 20.1 below. F2 + 2NO2 2NO2F Reaction 20.1 The mechanism for
- June 2022, Paper 1, Q16(b) (2 marks): Carbon monoxide also reacts with nitrogen dioxide as shown in Reaction 16.2. CO(g) + NO2(g) NO(g) + CO2(g) Reaction 16.2 The rate equation for Reaction 16.2 is
- November 2021, Paper 1, Q21(a)(ii) (2 marks): Predict a possible two-step mechanism for Reaction 21.1. The first step is the rate-determining step. Step 1 Step 2 [2]
- November 2021, Paper 3, Q4(c)(i) (2 marks): Write equations to suggest a two-step mechanism for the reaction. Slow Fast [2]
- June 2018, Paper 1, Q17(a) (6 marks): This question is about reaction rates. Aqueous iron(III) ions, Fe3+(aq), react with aqueous iodide ions, I–(aq), as shown below. 2Fe3+(aq) + 2I–(aq) 2Fe2+(aq) +
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? OCR A-Level Chemistry A past papers, or our free OCR-style practice pack.
The Plumi iPad app also offers exam-style questions with AI feedback on your handwritten working.