plumiReactions and tests of carbonyl compounds: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 15.B.2 Reactions and tests of carbonyl compounds, 2019–2025, with mark schemes and examiner’s reports where available.
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All 83 questions on Reactions and tests of carbonyl compounds, as a list
- June 2025, Unit 4, Q1(a) (1 mark): Propanone reacts with hydrogen cyanide, HCN, in the presence of potassium cyanide, KCN. How is this reaction classified? (1) A electrophilic addition B electrop
- June 2025, Unit 4, Q1(b) (1 mark): What is the first step in the mechanism of the reaction between propanone and a mixture of HCN and KCN? (1) A the lone pair of electrons on the carbon of CN− a
- June 2025, Unit 4, Q1(c) (1 mark): What is the name of the organic product formed in part (a)? (1) A 2-hydroxy-2-methylpropylamine B 2-hydroxy-2-methylethylamine C 2-hydroxy-2-methylethanenitrile
- June 2025, Unit 4, Q1(d) (1 mark): Which of these carbonyl compounds would produce pale yellow crystals when warmed with iodine in the presence of sodium hydroxide? (1) A butanone B butanal C pen
- June 2025, Unit 4, Q1(e) (1 mark): What is the formula of the pale yellow crystals formed in part (d)? (1) A CI4 B CHI3 C CH2I2 D CH3I
- June 2025, Unit 5, Q11(b) (1 mark): What type of reaction mechanism is taking place in step B? (1) A electrophilic addition B electrophilic substitution C nucleophilic addition D nucleophilic subs
- June 2025, Unit 5, Q11(c) (1 mark): What are the reagents used in step B? (1) A KCN and NaOH B HCN and KCN C HCl and KNO2 D HNO3 and H2SO4
- January 2025, Unit 4, Q16(b) (2 marks): Give a chemical test which distinguishes between pentan‑2‑one and pentan‑3‑one, CH3CH2COCH2CH3 . Include the results for both substances. (2)
- January 2025, Unit 4, Q16(c) (2 marks): Give a different chemical test which distinguishes between pentan‑2‑one and pentanal, CH3CH2CH2CH2CHO . Include the results for both substances. (2)
- January 2025, Unit 4, Q16(d) (3 marks): Pentan‑2‑one, pentan-3-one and pentanal react in a similar way with one test reagent to form solid products. Identify the reagent and describe how these solid p
- January 2025, Unit 4, Q16(e) (4 marks): Pentan‑2‑one and pentan-3-one both react with hydrogen cyanide in the presence of KCN. With pentan‑2‑one a racemic mixture is formed but with pentan‑3‑one there
- January 2025, Unit 6, Q3(a) (4 marks): Qualitative tests on X show that it • burns in air with a very smoky flame • forms an orange precipitate with 2,4-dinitrophenylhydrazine (Brady’s reagent) does
- October 2024, Unit 4, Q10(b) (1 mark): OH and OH (1) A warm each compound with Tollens’ reagent B add sodium carbonate solution to each compound C warm each compound with iodine under alkaline condit
- October 2024, Unit 4, Q10(c) (1 mark): O and O (1) A warm each compound with Tollens’ reagent B add sodium carbonate solution to each compound C warm each compound with iodine under alkaline conditio
- October 2024, Unit 4, Q14(a) (1 mark): What solvent is used in this reaction? (1) A ethanol B ether C ethyl ethanoate D water
- October 2024, Unit 4, Q18(a)(i) (4 marks): Complete the mechanism for the reaction. Include curly arrows, the structure of the intermediate, and any relevant lone pairs and dipoles. (4) H3C slow C O H CN
- October 2024, Unit 4, Q18(a)(ii) (2 marks): Explain why a small amount of sodium hydroxide solution is added to the reaction mixture, by considering the nature of the attacking species in the slow step. (
- October 2024, Unit 4, Q18(d) (6 marks): Carbonyl compounds can be identified from their 2,4‑dinitrophenylhydrazine derivatives. Describe this process, including in your answer • observations you would
- October 2024, Unit 5, Q19(d) (1 mark): The second step of the industrial preparation of the raspberry ketone involves the reduction shown. O O H2 catalyst HO HO Suggest why the choice of reducing age
- June 2024, Unit 4, Q10 (1 mark): Propanone reacts with HCN in the presence of KCN. Which of these statements is incorrect? A CN– acts as a nucleophile in the reaction B a racemic mixture is for
- June 2024, Unit 4, Q18(a) (4 marks): Propanal and propanone react similarly with lithium tetrahydridoaluminate(III). Complete the table about these reactions. (4) Formula of lithium tetrahydridoalu
- June 2024, Unit 4, Q18(b) (2 marks): State what would be seen when separate samples of propanal and propanone are warmed with Tollens’ reagent. (2)
- June 2024, Unit 4, Q18(c) (3 marks): When propanone reacts with iodine in the presence of aqueous sodium hydroxide, a yellow precipitate is observed. Write an equation for this reaction. Include st
- June 2024, Unit 4, Q18(d) (3 marks): Propanal and propanone both react with 2,4‑dinitrophenylhydrazine. The products of these reactions may be used to distinguish between separate samples of propan
- June 2024, Unit 4, Q18(e) (4 marks): Propanone, CH3COCH3, reacts with hydroxylamine, NH2OH, under mildly acidic conditions. The first stage of the reaction is a nucleophilic addition. Add curly arr
- June 2024, Unit 6, Q1(b) (1 mark): Test 3 A few drops of A are added to 2 cm3 of Tollens’ reagent (ammoniacal silver nitrate solution). The mixture is placed in a warm water bath. Observation sil
- January 2024, Unit 4, Q11(b) (1 mark): Which reagent gives a positive result when added to carvone? (1) A ammoniacal silver nitrate (Tollens’ reagent) B aqueous sodium carbonate C iodine in the prese
- January 2024, Unit 4, Q18(a) (2 marks): Name the reagent(s) in Step 1 and Step 2. (2) Step 1 Reagent(s) Step 2 Reagent(s)
- January 2024, Unit 4, Q18(b)(i) (4 marks): Complete the mechanism for Step 1, using curly arrows and relevant lone pairs, charges and dipoles. (4) H H H C C O H –C N
- January 2024, Unit 6, Q2(a) (2 marks): A sample of W gave a positive result with Tollens’ reagent. Give the positive result and the displayed formula of W. (2)
- January 2024, Unit 6, Q2(c)(i) (2 marks): Give two observations of a positive result from this test. (2)
- January 2024, Unit 6, Q2(c)(ii) (1 mark): Identify Y by name or formula. (1)
- October 2023, Unit 4, Q14(a)(i) (1 mark): Give the IUPAC name of the organic product. (1)
- October 2023, Unit 4, Q14(a)(ii) (4 marks): Complete the mechanism for this two‑step reaction, showing the structure of the intermediate and including curly arrows, and relevant lone pairs and dipoles. (4
- October 2023, Unit 4, Q14(a)(iii) (2 marks): Justify the use of the term ‘nucleophilic addition’ to describe the mechanism of this reaction. (2)
- October 2023, Unit 4, Q17(a) (6 marks): These four isomers can be identified using three chemical tests. Each test gives a positive result for only one isomer. All three tests give a negative result f
- June 2023, Unit 4, Q21(a) (2 marks): Complete the table for hexane-2,5-dione. Name the organic product formed if a reaction takes place. (2) Reaction Reagent and conditions Name of organic product
- June 2023, Unit 4, Q21(b) (1 mark): State the observation when hexane-2,5-dione reacts with iodine in the presence of alkali. (1)
- June 2023, Unit 4, Q21(c)(i) (1 mark): Name the type and mechanism of this reaction. (1)
- June 2023, Unit 4, Q21(c)(ii) (1 mark): Draw the structure of the product. (1)
- June 2023, Unit 4, Q21(d)(i) (1 mark): Give the observation when 2,4-dinitrophenylhydrazine (Brady’s reagent) reacts with hexane-2,5-dione. (1)
- June 2023, Unit 4, Q21(d)(ii) (2 marks): Describe, in outline, how the product of this reaction may be used to confirm the identity of hexane-2,5-dione. Experimental details are not required. (2)
- January 2023, Unit 4, Q15 (1 mark): Samples of ethanal and propanone are added to separate test tubes containing iodine dissolved in aqueous potassium hydroxide and the mixtures are heated gently.
- January 2023, Unit 4, Q19(a) (1 mark): State the essential condition for using LiAlH4. (1)
- January 2023, Unit 4, Q19(b) (4 marks): Complete the mechanism for the reduction of propanone with LiAlH4, showing the structure of the intermediate and of the final product. Include curly arrows, and
- January 2023, Unit 4, Q19(c) (3 marks): Explain why LiAlH4 reduces carbonyl compounds but not alkenes, even though both types of compound have π bonds. (3)
- October 2022, Unit 4, Q12 (1 mark): Which compound forms a precipitate with Fehling's or Benedict’s solutions and with iodine in the presence of alkali? A methanal B ethanal C propanone D butanone
- October 2022, Unit 4, Q15(c)(i) (1 mark): State what is meant by racemic lactic acid. (1)
- October 2022, Unit 4, Q15(c)(ii) (4 marks): Complete the mechanism for the formation of X in Step 1. Include curly arrows, and any relevant lone pairs and dipoles. (4) O H CN–
- June 2022, Unit 4, Q6 (1 mark): Which alcohol could not be formed by the reduction of an aldehyde or a ketone? A 2‑methylpentan‑1‑ol B 3‑methylpentan‑2‑ol C 3‑methylpentan‑3‑ol D 2‑methylpenta
- June 2022, Unit 4, Q17(a) (3 marks): Three carbonyl compounds, A, B and C, are straight‑chain structural isomers, with the formula C5H10O. Only isomer A reacts with Tollens’ reagent to give a silve
- June 2022, Unit 4, Q17(b)(i) (1 mark): Give the IUPAC name for CH3CH2CH(OH)CN. (1)
- June 2022, Unit 4, Q17(c)(i) (1 mark): Propanone, an isomer of propanal, also reacts with HCN in the presence of KCN. Draw the skeletal formula of the product of this reaction. (1)
- June 2022, Unit 6, Q2(a)(i) (3 marks): The student carries out three tests on separate samples of each compound. Complete Table 1 to show the observations that the student makes. (3) Observations on
- June 2022, Unit 6, Q2(a)(ii) (1 mark): Identify, by name or formula, the pale yellow precipitate that forms when iodine and sodium hydroxide are added to a sample of D. (1)
- June 2022, Unit 6, Q2(b)(ii) (2 marks): The melting temperatures of the derivatives of the reaction of Brady’s reagent with some aldehydes and ketones are shown. Melting temperature of the derivative
- January 2022, Unit 4, Q11 (1 mark): How many structural isomers with the molecular formula C5H10O react with Tollens’ reagent? A 2 B 3 C 4 D 5 Use this space for any rough working. Anything you wr
- January 2022, Unit 4, Q12(a) (1 mark): The products of the reactions under the stated conditions include (1) Acidic conditions Alkaline conditions CH3I A CH3COO– CH3COCI3 B CH3COO– CH3COCH2I CH3I C C
- January 2022, Unit 4, Q19(a)(i) (4 marks): Complete the mechanism for this reaction by adding curly arrows, and relevant lone pairs and dipoles to Step 1 and Step 2. (4) H H H H H H Step 1 O– H C C C H C
- January 2022, Unit 4, Q19(a)(ii) (2 marks): Explain why the reaction between propanal and HCN in the absence of KCN is very slow, referring to the value of Ka. No calculation is required. [For HCN, Ka = 4
- January 2022, Unit 4, Q19(a)(iii) (2 marks): KCN is a homogeneous catalyst in this reaction. Justify this description by referring to the mechanism. (2)
- January 2022, Unit 5, Q10(b)(i) (2 marks): Complete the equation for the reaction. (2) OH OH O HO H + [Ag(NH3)2]+ + OH− OH OH glucose C6H12O7 + Ag + + Y
- January 2022, Unit 5, Q10(b)(ii) (1 mark): Draw the structure of Y. (1)
- January 2022, Unit 6, Q2(b) (3 marks): Three chemical tests are carried out on X. Test 1 When Brady’s reagent (2,4‑dinitrophenylhydrazine solution) is added to X, an orange precipitate is observed.
- October 2021, Unit 4, Q12 (1 mark): An unknown aldehyde may be identified by measuring the melting temperature of the purified precipitate formed in its reaction with A 2,4-dinitrophenylhydrazine
- October 2021, Unit 4, Q16(b)(ii) (3 marks): Give a chemical test which would allow you to distinguish between the two compounds you have given in (b)(i). Include the reagents required and the result for e
- October 2021, Unit 5, Q21(b) (2 marks): Selenide anions attached to protein side‑chains may undergo nucleophilic addition reactions with curcumin. Complete the mechanism for one of the steps in such a
- October 2021, Unit 6, Q2(a)(i) (2 marks): Complete the statements in the inference column by writing the names or formulae of the functional groups. (2) Test Observation Inference Test 1 A could contain
- October 2021, Unit 6, Q2(a)(ii) (1 mark): Give the name or formula of the red precipitate formed in Test 2. (1)
- June 2021, Unit 4, Q8(c) (1 mark): Four groups of students warmed samples of menthol with sodium dichromate(VI) in acid. They purified the reaction mixture and carried out a series of qualitative
- June 2021, Unit 4, Q19(a)(i) (4 marks): Give the mechanism for Step 1. Include curly arrows, and any relevant lone pairs and dipoles. (4)
- June 2021, Unit 6, Q3(b)(i) (2 marks): A and B O O OH OH O B A (2)
- June 2021, Unit 6, Q3(b)(ii) (2 marks): C and D O O O C D (2)
- January 2021, Unit 4, Q13 (1 mark): A compound X, with molecular formula C5H10O , gave an orange precipitate with 2,4-dinitrophenylhydrazine. X gave a silver mirror with Tollens’ reagent. Which of
- January 2021, Unit 4, Q19(b) (4 marks): Ethanal, CH3CHO , reacts with hydrogen cyanide in the presence of cyanide ions to form 2-hydroxypropanenitrile. Draw the mechanism for this reaction. Include cu
- January 2021, Unit 4, Q19(c)(i) (1 mark): F reacts with iodine in an alkaline solution to give a pale yellow precipitate. Give the name or formula of the group in F identified by this test. (1)
- October 2020, Unit 4, Q10 (1 mark): Which diagram shows the first step of the mechanism for the nucleophilic addition of hydrogen cyanide to propanone in the presence of potassium cyanide? δ− O O–
- October 2020, Unit 4, Q11 (1 mark): When propanone reacts with iodine in the presence of sodium hydroxide, the precipitate formed has the formula A CH3I B CHI3 C CH3COCH2I D CH3COCI3
- October 2020, Unit 4, Q15(a) (1 mark): Which test would distinguish between 2-methylpropan-2-ol, (CH3)3COH, and butanone, CH3CH2COCH3? (1) A B C D
- October 2020, Unit 4, Q15(c) (1 mark): Which test could not be used to distinguish between 2-methylpropan-2-ol, (CH3)3COH, and butanal, CH3CH2CH2CHO? (1) A B C D
- October 2020, Unit 4, Q17(c)(ii) (1 mark): State the conditions required and the reagent needed to form compound W from propanal. (1)
- January 2020, Unit 4, Q1(c) (1 mark): Which of these reacts with iodine and sodium hydroxide in solution to produce a pale yellow precipitate? (1) A compound 1 B compound 2 C compound 3 D compound 4
- January 2020, Unit 4, Q17 (6 marks): *17 Compare and contrast the reactions of propanal and propanone with one oxidising agent, one reducing agent and 2,4-dinitrophenylhydrazine. In your answer inc
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