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Amino acids, amides and chirality

Past-paper questions pack

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Questions are numbered; the mark schemes (the answer key) follow on separate pages so the question pages can be handed out alone. www.chemistryaleveltutor.com

OCR AS and A-level Chemistry past-paper questions since 2016 · 50 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · Paper 2 · Q7 · 1 marks ·
7 What are the organic products of the acid hydrolysis of CH3CH2CONHCH3? A CH3CH2COO– + CH3NH3 + B CH3CH2COOH + CH3NH3 + C CH3CH2COOH + CH3NH2 D CH3CH2COO– + CH3NH2 Your answer [1]
2. June 2025 · Paper 2 · Q10 · 1 marks ·
10 How many stereoisomers does the compound CH3CH(Br)CH=CHCH(Cl )CH3 have? A 2 B 4 C 6 D 8 Your answer [1]
3. June 2025 · Paper 2 · Q22(a)(ii) · 2 marks ·
(ii) Compound S has two possible structures. Draw both of these structures. [2]
4. June 2025 · Paper 2 · Q22(b)(ii) · 1 marks ·
(ii) α-Amino acids have the NH2 group bonded to the carbon atom adjacent to the carboxylic acid group. Suggest the difference between an α-keto acid and a β-keto acid. .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [1]
5. June 2025 · Paper 3 · Q4(b)(ii) · 3 marks ·
(ii) Complex A can be prepared by reacting an aqueous solution of nickel(II) sulfate with amino acid B and potassium hydroxide. Aqueous nickel(II) sulfate contains the octahedral hexaaquo complex ion C. Draw the structure of amino acid B and the 3D structure, including the overall charge, of complex ion C. Amino acid B Complex ion C [3]
6. June 2024 · Paper 2 · Q9 · 1 marks ·
9 Which compound is a secondary amide? N A OH O N C B H O O C N H OH NH2 D HO C O Your answer [1]
7. June 2024 · Paper 2 · Q22(a) · 3 marks ·
22 α-Amino acids have the general formula RCH(NH2)COOH. The R group in an α-amino acid contains C and H only. This R group has a molar mass of 91 g mol –1. (a) A polymer is formed from 500 molecules of this α-amino acid. Determine the molar mass of this polymer. Give your answer to the nearest whole number. molar mass of polymer = .............................................. g mol –1[3]
8. June 2024 · Paper 3 · Q2(c)(ii) · 1 marks ·
(ii) How many chiral carbon atoms are there in one molecule of compound B? ..................................................................................................................................................... [1]
9. June 2023 · Paper 2 · Q4 · 1 marks · AO1
4 The structure of the painkiller paracetamol is shown below. OH O N H Paracetamol Which functional groups are present in paracetamol? A alcohol, amide B alcohol, arene, ketone, amine C phenol, amide D phenol, ketone, amine Your answer [1]
10. June 2023 · Paper 2 · Q21(a) · 1 marks · AO1
21 This question is about α-amino acids. (a) The general formula of an α-amino acid is RCH(NH2)COOH. Most α-amino acids show optical isomerism. Explain the term optical isomerism. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [1]
11. June 2023 · Paper 2 · Q21(b)(ii) · 2 marks · AO1
(ii) Draw diagrams to show 3D structures of the optical isomers of valine. [2]
12. June 2023 · Paper 2 · Q21(c)(i) · 1 marks · AO2
(c) Three α-amino acids can react together to form compound E, shown below. OH OH C H2C O H H2C N CH CH C NH C O C NH2 HO O O CH CH HO CH3 Compound E (i) How many optical isomers are possible for compound E? ...................................................................................................................................... [1]
13. June 2023 · Paper 2 · Q21(c)(ii) · 4 marks · AO2
(ii) A student hydrolyses compound E with dilute hydrochloric acid, HCl (aq). Draw the structures of the organic products formed by this hydrolysis. [4]
14. June 2023 · Paper 3 · Q3 · 6 marks · AO3
3* A chemist is investigating compound A, shown below, as a potential organic intermediate. O OH CN Compound A Describe the type of stereoisomerism shown by compound A and suggest three reactions of compound A, one for each of the three functional groups using reagents of your choice. In your answer, show stereoisomers of compound A, your chosen reactants and conditions, and the structures for the organic products produced. Mechanisms and equations are not required. 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Additional answer space if required. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..........................................................................................................................................................
15. June 2022 · Paper 2 · Q4 · 1 marks · AO1
4 The skeletal formula of an organic compound is shown below. N OH O Which functional groups are present? A amide and alcohol B amide and carboxylic acid C amine and carboxylic acid D amine, ketone and alcohol Your answer [1]
16. June 2022 · Paper 2 · Q5 · 1 marks · AO1
5 The structure of a drug is shown below: O HO OH HO F O How many chiral carbon atoms are there in a molecule of the drug? A 5 B 6 C 7 D 8 Your answer [1]
17. June 2022 · Paper 2 · Q16(b)(iv) · 2 marks · AO2
(iv) Draw 3D structures for the optical isomers of compound C. Optical isomers [2]
18. June 2022 · Paper 2 · Q17 · 6 marks · AO1, 2
17 This question is about an analysis of an unknown organic Compound X. Some properties of Compound X are shown in the table. Molecular formula Functional groups Chirality C–F CxHyF6O 1 chiral carbon C–O–C At a pressure of 1.07 × 105 Pa at 30 °C, 1.327 g of Compound X is a gas with a volume of 186 cm3. Determine the molar mass of Compound X and its molecular formula. Draw a possible structure for a molecule of Compound X. molar mass ................................................... g mol–1 molecular formula ............................................................... Structure of Compound X [6]
19. June 2022 · Paper 2 · Q19(a) · 4 marks · AO2
19 This question is about compounds that contain the carboxylic acid functional group. (a) Carboxylic acids react with alkalis, metals and carbonates to form salts. Write full equations for the following three reactions. Show structures for organic compounds. • the reaction of propanoic acid with aqueous potassium hydroxide: • the reaction of aqueous methanoic acid with magnesium: • the reaction of the α–amino acid, aspartic acid (R=CH2COOH), with an excess of aqueous sodium carbonate, Na2CO3: [4]
20. June 2022 · Paper 2 · Q19(e) · 6 marks · AO3
(e)* A student intends to synthesise compound I. O O NH2 Compound I Plan a synthesis to prepare 9.36 g of compound I starting from 2-chloropropanoic acid, CH3CHCl COOH. The overall percentage yield of compound I from 2-chloropropanoic acid is 64%. In your answer, include starting mass of 2-chloropropanoic acid, reagents, conditions and equations where appropriate. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
21. June 2022 · Paper 3 · Q6(a) · 1 marks · AO2
6 A student carries out an investigation on vitamin C, C6H8O6. (a) The structure of vitamin C is shown below. Vitamin C is an optical isomer. O O H H H O O O O H Vitamin C What is the total number of optical isomers with the structure of vitamin C? total number of optical isomers = ......................................................... [1]
22. November 2021 · Paper 2 · Q2 · 1 marks ·
2 Which type(s) of stereoisomerism is/are shown by 2,4-dimethylhex-2-ene? A E / Z isomerism only. B Optical isomerism only. C Both E / Z isomerism and optical isomerism. D Neither E / Z isomerism nor optical isomerism. Your answer [1]
23. November 2021 · Paper 2 · Q5 · 1 marks ·
5 2-Methylcyclopentanone, shown below, is reacted with NaCN(aq)/H+(aq) to form an organic product. O CH3 2-methylcyclopentanone Which statement is correct? A In the mechanism, a CN– ion accepts an electron pair. B The mechanism is electrophilic addition. C The organic product has one chiral centre. D The organic product has the molecular formula C7H11NO. Your answer [1]
24. November 2021 · Paper 2 · Q18(a)(i) · 1 marks · AO1
18 This question is about organic acids. (a) Table 18.1 shows the R groups in four amino acids. Amino acid R group alanine CH3– valine (CH3)2CH– threonine CH3CH(OH)– lysine H2N(CH2)4– Table 18.1 Most amino acids show optical isomerism. (i) Explain the term optical isomerism. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
25. November 2021 · Paper 2 · Q18(a)(ii) · 2 marks · AO2
(ii) Draw 3-D diagrams to show the optical isomers of alanine. [2]
26. November 2021 · Paper 2 · Q18(a)(iii) · 1 marks · AO2
(iii) How many optical isomers does threonine have? ...................................................................................................................................... [1]
27. November 2021 · Paper 2 · Q18(d)(i) · 2 marks · AO3
(d) Tablets based on ibuprofen and lysine are now available from pharmacies. These tablets are claimed to act faster than ibuprofen by being absorbed into the body more quickly than ibuprofen alone. One type of these tablets contains a salt of ibuprofen and the amino acid lysine (R = –(CH2)4NH2) in a 1:1 molar proportion. (i) Suggest the structure of each ion in this lysine salt of ibuprofen, including the position of any charges. – ion + ion [2]
28. November 2020 · Paper 2 · Q16(b)(i) · 1 marks · AO1
(b) (CH3)3CCHBrCH3has stereoisomers. (i) Explain the term stereoisomers and name this type of stereoisomerism. Explanation: ...................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Type of stereoisomerism: ............................................................................................. [1]
29. November 2020 · Paper 2 · Q16(b)(ii) · 2 marks · AO1, 2
(ii) Draw 3D diagrams for the stereoisomers of (CH3)3CCHBrCH3. [2]
30. November 2020 · Paper 2 · Q17(c)(ii) · 5 marks · AO3
(ii) The chemist develops a three-stage synthesis of compound D from compound C. Complete the flowchart. Show structures for organic compounds. reagent: ...................................... catalyst: ...................................... compound C 1. Sn + HCl 2. Neutralise O HN reagent: ...................................... compound D [5]
31. November 2020 · Paper 2 · Q21(b)(i) · 3 marks · AO1
(b) Aspartame, shown below, is an artificial sweetener commonly used as a sugar substitute. O NH2 O H N O OH O aspartame (i) Aspartame contains several functional groups. Apart from the benzene ring, name the functional groups in aspartame. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
32. November 2020 · Paper 2 · Q21(b)(ii) · 4 marks · AO2
(ii) A sample of aspartame is hydrolysed with aqueous acid. Draw the structures of the three organic products of the complete acid hydrolysis of aspartame. [4]
33. November 2020 · Paper 3 · Q1(c) · 2 marks · AO3
(c) The amino acid Z−H2NCH=CHCOOH can react to form a cyclic compound with the molecular formula C3H3NO and one other product. Complete the equation for this reaction. H2N COOH C C + H H [2]
34. June 2019 · Paper 2 · Q7 · 1 marks · AO1
7 What is the number of chiral carbon atoms in the steroid molecule below? OH O A 5 B 6 C 7 D 8 Your answer [1]
35. June 2019 · Paper 2 · Q15 · 1 marks · AO1
15 The structure of a compound used to treat influenza is shown below. O O O HN NH2 O Which functional group(s) is/are in a molecule of the compound? 1 Ester 2 Secondary amide 3 Ketone A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
36. June 2019 · Paper 2 · Q16(b)(v) · 4 marks · AO1, 2
(v) The structures of geraniol and citronellal are repeated below with the carbon atoms numbered. 7 1 1 7 5 4 3 5 4 3 2 8 OH 8 6 2 6 O Geraniol Citronellal Explain the types of stereoisomerism shown by geraniol and citronellal. In your answer, • refer to the numbered carbon atoms in the structures above • draw diagrams clearly showing any stereoisomers. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Geraniol stereoisomers Citronellal stereoisomers [4]
37. June 2019 · Paper 2 · Q17(a)(i) · 4 marks · AO2
17 This question is about α-amino acids, RCH(NH2)COOH. (a) Table 17.1 shows the R groups in four amino acids. Amino acid R group alanine (ala) CH3– serine (ser) HOCH2– leucine (leu) (CH3)2CHCH2– glycine (gly) H– Table 17.1 (i) In the boxes, draw the organic products for the reactions of serine shown below. (CH3)2CHOH / H2SO4 H+(aq) H O excess CH3COCl H2N C C OH CH2 OH serine [4]
38. June 2019 · Paper 2 · Q17(a)(ii) · 4 marks · AO2, 3
(ii) A student is provided with one of the four amino acids in Table 17.1. A student carries out a titration with a standard solution of hydrochloric acid to identify the amino acid. The student’s method is outlined below. • The student dissolves 5.766 g of the amino acid in water and makes the solution up to 250.0 cm3 in a volumetric flask. • The student titrates this solution with 25.0 cm3 of 0.150 mol dm−3 hydrochloric acid. • 21.30 cm3 of the amino acid solution were required for complete neutralisation of the hydrochloric acid. Determine which amino acid the student used. [4]
39. June 2019 · Paper 3 · Q4(b)(i) · 1 marks · AO2
(b) Dettol® contains other chemicals including α-terpineol, shown below. (i) α-Terpineol is a chiral compound. Show with an asterisk, (*), the chiral centre(s) in the structure of α-terpineol. OH α-terpineol [1]
40. June 2018 · Paper 2 · Q2 · 1 marks ·
2 Which compound is a secondary amide? O CH3 A HO C CH2 N H O CH3 B HO C CH2 N CH3 O CH3 C H3C C N H O CH3 D H3C C N CH3 Your answer [1]
41. June 2018 · Paper 2 · Q11 · 1 marks ·
11 How many straight-chain structural isomers of C7H15Cl contain a chiral carbon atom? A 1 B 2 C 3 D 4 Your answer [1]
42. June 2018 · Paper 2 · Q17(a) · 2 marks ·
17 The general formula of an α-amino acid is RCH(NH2)COOH. (a) The α-amino acid cysteine (R = CH2SH) shows optical isomerism. Draw 3-D diagrams to show the optical isomers of cysteine. [2]
43. June 2018 · Paper 2 · Q17(b) · 2 marks ·
(b) The α-amino acid lysine (R = (CH2)4NH2) reacts with an excess of dilute hydrochloric acid to form a salt. Draw the structure of the salt formed in this reaction. [2]
44. June 2018 · Paper 2 · Q17(c) · 3 marks ·
(c) α-Amino acids can react to form proteins. A short section of a protein chain is shown below. HO CH2 H O CH N C N C CH H O CH2 CH2 C H2N O A student hydrolyses the protein with hot NaOH(aq). Draw the structures of the organic products formed from this section of the protein. [3]
45. June 2018 · Paper 2 · Q19(c)(ii) · 3 marks ·
(ii) Analyse the information to identify E, F and G. Show your working. [3]
46. June 2018 · Paper 3 · Q4(b)(i) · 2 marks ·
(b) Paracetamol is a solid organic compound used in tablets as a painkiller. H HO N C CH3 paracetamol O (i) Name the functional groups present in paracetamol. ...................................................................... ...................................................................... [2]
47. June 2017 · Paper 2 · Q7 · 1 marks ·
7 Which molecule is a secondary amine? NH N O O NH N O O A B C D Your answer [1]
48. June 2017 · Paper 2 · Q8 · 1 marks ·
8 What is the number of chiral centres in the molecule below? NH2 H N S O N HO O OH O A 2 B 3 C 4 D 5 Your answer [1]
49. June 2017 · Paper 2 · Q13 · 1 marks ·
13 Which reagents could be used to prepare CH3CH2CONHCH3? A CH3CH2COCl + CH3NH2 B CH3CH2CONH2 + CH3Br C CH3CH2COONa + CH3NH2 D CH3CH2COCH3 + NH3 Your answer [1]
50. June 2017 · Paper 3 · Q4(a)(ii) · 6 marks ·
(ii) The structure of compound A is shown below. O HO OH R compound A Compound A has four optical isomers. Using this information and the student’s results, answer the following. • Determine the molar mass of A and the formula of the alkyl group R. • Draw the structure of compound A and label any chiral carbon atoms with an asterisk*. Show all your working. [6]

Mark schemes

1. June 2025 · Paper 2 · Q7
Mark scheme June 2025 Paper 2 Q7
2. June 2025 · Paper 2 · Q10
Mark scheme June 2025 Paper 2 Q10
3. June 2025 · Paper 2 · Q22(a)(ii)
Mark scheme June 2025 Paper 2 Q22(a)(ii)
4. June 2025 · Paper 2 · Q22(b)(ii)
Mark scheme June 2025 Paper 2 Q22(b)(ii)
5. June 2025 · Paper 3 · Q4(b)(ii)
Mark scheme June 2025 Paper 3 Q4(b)(ii)
6. June 2024 · Paper 2 · Q9
Mark scheme June 2024 Paper 2 Q9
7. June 2024 · Paper 2 · Q22(a)
Mark scheme June 2024 Paper 2 Q22(a)
8. June 2024 · Paper 3 · Q2(c)(ii)
Mark scheme June 2024 Paper 3 Q2(c)(ii)
9. June 2023 · Paper 2 · Q4
Mark scheme June 2023 Paper 2 Q4
10. June 2023 · Paper 2 · Q21(a)
Mark scheme June 2023 Paper 2 Q21(a)
11. June 2023 · Paper 2 · Q21(b)(ii)
Mark scheme June 2023 Paper 2 Q21(b)(ii)
12. June 2023 · Paper 2 · Q21(c)(i)
Mark scheme June 2023 Paper 2 Q21(c)(i)
13. June 2023 · Paper 2 · Q21(c)(ii)
Mark scheme June 2023 Paper 2 Q21(c)(ii)
14. June 2023 · Paper 3 · Q3
Mark scheme June 2023 Paper 3 Q3
15. June 2022 · Paper 2 · Q4
Mark scheme June 2022 Paper 2 Q4
16. June 2022 · Paper 2 · Q5
Mark scheme June 2022 Paper 2 Q5
17. June 2022 · Paper 2 · Q16(b)(iv)
Mark scheme June 2022 Paper 2 Q16(b)(iv)
18. June 2022 · Paper 2 · Q17
Mark scheme June 2022 Paper 2 Q17
19. June 2022 · Paper 2 · Q19(a)
Mark scheme June 2022 Paper 2 Q19(a)
20. June 2022 · Paper 2 · Q19(e)
Mark scheme June 2022 Paper 2 Q19(e)
21. June 2022 · Paper 3 · Q6(a)
Mark scheme June 2022 Paper 3 Q6(a)
22. November 2021 · Paper 2 · Q2
Mark scheme November 2021 Paper 2 Q2
23. November 2021 · Paper 2 · Q5
Mark scheme November 2021 Paper 2 Q5
24. November 2021 · Paper 2 · Q18(a)(i)
Mark scheme November 2021 Paper 2 Q18(a)(i)
25. November 2021 · Paper 2 · Q18(a)(ii)
Mark scheme November 2021 Paper 2 Q18(a)(ii)
26. November 2021 · Paper 2 · Q18(a)(iii)
Mark scheme November 2021 Paper 2 Q18(a)(iii)
27. November 2021 · Paper 2 · Q18(d)(i)
Mark scheme November 2021 Paper 2 Q18(d)(i)
28. November 2020 · Paper 2 · Q16(b)(i)
Mark scheme November 2020 Paper 2 Q16(b)(i)
29. November 2020 · Paper 2 · Q16(b)(ii)
Mark scheme November 2020 Paper 2 Q16(b)(ii)
30. November 2020 · Paper 2 · Q17(c)(ii)
Mark scheme November 2020 Paper 2 Q17(c)(ii)
31. November 2020 · Paper 2 · Q21(b)(i)
Mark scheme November 2020 Paper 2 Q21(b)(i)
32. November 2020 · Paper 2 · Q21(b)(ii)
Mark scheme November 2020 Paper 2 Q21(b)(ii)
33. November 2020 · Paper 3 · Q1(c)
Mark scheme November 2020 Paper 3 Q1(c)
34. June 2019 · Paper 2 · Q7
Mark scheme June 2019 Paper 2 Q7
35. June 2019 · Paper 2 · Q15
Mark scheme June 2019 Paper 2 Q15
36. June 2019 · Paper 2 · Q16(b)(v)
Mark scheme June 2019 Paper 2 Q16(b)(v)
37. June 2019 · Paper 2 · Q17(a)(i)
Mark scheme June 2019 Paper 2 Q17(a)(i)
38. June 2019 · Paper 2 · Q17(a)(ii)
Mark scheme June 2019 Paper 2 Q17(a)(ii)
39. June 2019 · Paper 3 · Q4(b)(i)
Mark scheme June 2019 Paper 3 Q4(b)(i)
40. June 2018 · Paper 2 · Q2
Mark scheme June 2018 Paper 2 Q2
41. June 2018 · Paper 2 · Q11
Mark scheme June 2018 Paper 2 Q11
42. June 2018 · Paper 2 · Q17(a)
Mark scheme June 2018 Paper 2 Q17(a)
43. June 2018 · Paper 2 · Q17(b)
Mark scheme June 2018 Paper 2 Q17(b)
44. June 2018 · Paper 2 · Q17(c)
Mark scheme June 2018 Paper 2 Q17(c)
45. June 2018 · Paper 2 · Q19(c)(ii)
Mark scheme June 2018 Paper 2 Q19(c)(ii)
46. June 2018 · Paper 3 · Q4(b)(i)
Mark scheme June 2018 Paper 3 Q4(b)(i)
47. June 2017 · Paper 2 · Q7
Mark scheme June 2017 Paper 2 Q7
48. June 2017 · Paper 2 · Q8
Mark scheme June 2017 Paper 2 Q8
49. June 2017 · Paper 2 · Q13
Mark scheme June 2017 Paper 2 Q13
50. June 2017 · Paper 3 · Q4(a)(ii)
Mark scheme June 2017 Paper 3 Q4(a)(ii)