plumiOptical activity and racemic mixtures: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 15.A.2 Optical activity and racemic mixtures, 2019–2025, with mark schemes and examiner’s reports where available.
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Q19(a)(v)
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Open the full PDFYour answerQ18(a)
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All 10 questions on Optical activity and racemic mixtures, as a list
- June 2025 (A), Unit 5, Q19(a)(v) (3 marks): Alanine exists as two optical isomers. Explain how this type of isomerism occurs, stating how the isomers may be distinguished. (3)
- January 2024, Unit 4, Q18(b)(ii) (3 marks): Explain why the 2‑hydroxypropanoic acid, CH3CH(OH)COOH, produced is not optically active. (3)
- January 2024, Unit 5, Q10(c) (1 mark): Which of the esters could rotate the plane of plane‑polarised monochromatic light? (1) A Q only B Q and R C Q, R and S D R and S
- October 2023, Unit 4, Q14(b) (2 marks): Explain why the product of the reaction is not optically active even though it contains a chiral carbon atom. (2)
- June 2023, Unit 4, Q5 (1 mark): Which pair of compounds can form a racemic mixture when mixed? CH2OH CH2OH A H H C2H5 CH2OH HO H3C CH2OH CH2OH B H H C2H5 C2H5 HO HO CH3 CH3 C H HO C2H4OH CH2OH
- January 2023, Unit 4, Q18(a) (6 marks): Explain why lactic acid formed in muscles is optically active while lactic acid obtained using the laboratory synthesis is not. You should define any terms you
- June 2022, Unit 4, Q17(b)(ii) (1 mark): Describe how you could distinguish between pure samples of the two optical isomers. (1)
- June 2022, Unit 6, Q4(b)(ii) (2 marks): The limonene extracted from orange peel is D‑limonene. State how the presence of a single optical isomer could be confirmed, naming the apparatus used. No exper
- June 2021, Unit 4, Q19(a)(ii) (3 marks): A student predicted that the product of Step 1 would rotate the plane of plane-polarised light. Comment on this prediction. (3)
- January 2021, Unit 4, Q17(a)(ii) (1 mark): A laboratory sample of lactic acid does not rotate the plane of plane-polarised monochromatic light. Give a reason for this observation. (1)
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