Mass spectra and IR: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on 10D Mass spectra and IR (specification points 10.21–10.23), 2019–2025, with its mark scheme and examiner’s report.

All 63 questions on Mass spectra and IR, as a list

June 2025, AS Unit 2, Q12(a) (1 mark): Which compound has peaks in its mass spectrum at m/z 74 and 45? (1) A butanone B butanal C butan-2-ol D methylpropan-2-ol
June 2025, AS Unit 2, Q16(c)(ii) (2 marks): The infrared spectrum of cyclohexanol is shown. Transmittance 3000 2000 1000 Wavenumber / cm–1 Describe two differences, other than the fingerprint region, that
June 2025, AS Unit 3, Q1(c) (3 marks): Mass spectra of P and Q show a molecular ion peak at m / z = 60. The mass spectrum of P has its most intense peak at m / z = 31 and this peak is not present in
June 2025, AS Unit 3, Q1(d) (2 marks): Deduce the structural formulae of P and Q. (2) P Q
June 2025, Unit 5, Q20(c) (2 marks): The infrared spectrum for salicylic acid is shown. 100 Transmittance / % 50 0 4000 3000 2000 1500 1000 500 Wavenumber / cm–1 Identify two wavenumbers on the spe
June 2025 (A), Unit 5, Q18(c) (3 marks): There are two possible products in Step 4. Describe how these could be distinguished using infrared spectroscopy. Refer to three different types of bond and the
January 2025, AS Unit 2, Q20 (6 marks): *20 A bottle has lost its label. The content of the bottle is thought to be one of 1-hydroxypropanone, propenoic acid or butan-1-ol. O O OH OH OH 1-hydroxypropa
October 2024, AS Unit 2, Q14(b) (1 mark): Which compound could give peaks at m / z = 31 and m / z = 60 in its mass spectrum? (1) A propan-1-ol B propan-2-ol C propanal D propanone Use this space for any
October 2024, AS Unit 2, Q15 (1 mark): An infrared spectrum for a compound containing one functional group is shown. 100 Transmittance / % 50 0 4000 3000 2000 1500 1000 500 Wavenumber / cm–1 Which fu
June 2024, AS Unit 2, Q20(a)(ii) (2 marks): The peaks with the highest intensity in the mass spectrum of isoprene are at m / z = 68 and m / z = 53. Identify the species responsible for these two peaks. (2
June 2024, AS Unit 2, Q20(a)(iii) (3 marks): The infrared spectrum of isoprene is shown. R P Transmittance Q / % 3000 2000 1000 Wavenumber / cm–1 State the origins of the peaks labelled P, Q and R. You may
June 2024 (R), AS Unit 2, Q20(b)(ii) (3 marks): Acetoin also contains the carbonyl group C an aldehyde. Use page 5 of your Data Booklet to show how infrared spectra data could be used to prove that acetoin co
June 2024 (R), AS Unit 2, Q20(b)(iii) (3 marks): Part of the mass spectrum of acetoin is shown. 100 80 60 Relative intensity 40 20 0.0 15 30 45 60 75 90 m / z Determine a possible structure of acetoin using yo
January 2024, AS Unit 2, Q20 (1 mark): Which compound gives this mass spectrum? 100 80 60 Relative intensity 40 20 0 10 15 20 25 30 35 40 45 50 55 60 m / z A CH3COOH B CH3COCH3 C CH3CH2CHO D CH3CH2CH
January 2024, AS Unit 2, Q23(c)(iii) (2 marks): Give the wavenumber range of an absorption in the infrared spectrum of the organic product of reaction R4, which is not present in the infrared spectrum of CH3C
January 2024, AS Unit 3, Q1(c)(i) (1 mark): Deduce the m/z ratio of the fragment shown by the unshaded area, assuming it forms a singly charged ion. (1)
January 2024, AS Unit 3, Q1(c)(ii) (1 mark): When molecular ions fragment, they form a smaller ion and another type of particle. State the other type of particle formed. (1)
January 2024, Unit 4, Q15(a) (1 mark): The mass spectrum of compound X shows a large peak at m/z = 59. This peak is due to the fragmentation of the molecular ion. Which compound is most likely to be
January 2024, Unit 4, Q15(b) (1 mark): Compound Y does not react with acidified aqueous sodium dichromate. The infrared spectrum of Y is shown. 100 % Transmittance 0 3000 2000 1000 Wavenumber / cm–1
January 2024, Unit 6, Q4(f) (3 marks): An infrared spectrum of phenylethanamide and an infrared spectrum of phenylamine were obtained. One of these two spectra is shown with two peaks circled. 100 Tr
October 2023, AS Unit 2, Q14(a) (1 mark): When propan‑2‑ol is refluxed with excess acidified potassium dichromate(VI), the product will show a peak due to (1) A O H stretching at 3750 – 3200 cm–1 B C O
October 2023, AS Unit 2, Q14(b) (1 mark): When propan‑1‑ol is heated with acidified potassium dichromate(VI), the product that is distilled off as it is formed will show a peak due to (1) A O H stretchi
October 2023, AS Unit 2, Q21(a)(ii) (2 marks): The mass spectrum of X is shown. 100 80 60 Percentage relative 40 abundance 20 0.0 30 40 50 60 70 80 90 m / z Deduce the molecular formula of X, using the mass
October 2023, AS Unit 2, Q21(a)(iv) (2 marks): Using your answer to (a)(iii) and the mass spectrum, complete Table 2. (2) Table 2 Peak in mass spectrum Formula of ion m / z = 41 m / z = 45
June 2023, AS Unit 2, Q21(c) (2 marks): Explain how the infrared spectra of methanol and methanal can be used to distinguish between the two compounds, stating the relevant bond stretching vibrations
June 2023, AS Unit 3, Q2(d)(ii) (1 mark): Some infrared data are given in the table. Group Wavenumber range / cm–1 O H stretching in alcohols 3750–3200 O H stretching in carboxylic acids 3300–2500 C O s
June 2023, AS Unit 3, Q2(d)(iii) (2 marks): A student suggested that the structure of D could be identified using mass spectrometry because only one of the possible structures of D would have a peak at m
June 2023, Unit 6, Q2(c)(i) (1 mark): Bubbles are observed when aqueous sodium hydrogencarbonate is added to Y. Deduce the formula of the ion responsible for the peak at m / z = 45. (1)
January 2023, AS Unit 2, Q15 (1 mark): Which compound is least likely to have a prominent peak at m / z = 43 in its mass spectrum? A CH3COCH2CH3 B CH3CH2NHCH3 C CH3CH(CH3)2 D CH3CH2CH2CH3
January 2023, AS Unit 2, Q16 (1 mark): Which compound has peaks at 3415 cm–1 and 2250 cm–1 in its infrared spectrum? Refer to the Data Booklet. A H2NCH2CH2C N B CH3CH2CH2COOH C ClCH2CH2C CH D HOCH2CH
January 2023, Unit 5, Q11(a) (1 mark): Which of these wavenumber ranges would you not expect to have an absorption in the infrared spectrum of valine? (1) A 3500 – 3300 cm–1 B 3095 – 3010 cm–1 C 2962
October 2022, AS Unit 2, Q22(c)(iii) (2 marks): Infrared spectroscopy provides information on functional groups. In an experiment, a sample of 2-methylpropan-1-ol was treated with an oxidising agent. Show tha
June 2022, AS Unit 2, Q14(c) (1 mark): Cyclohexanol and cyclohexene each has a peak in their infrared spectrum which is not present for the other compound. Which are these peaks? (1) Peak only in cyc
January 2022, AS Unit 2, Q24(d)(i) (1 mark): Draw a circle around an absorption in the spectrum that could be due to the stretching of the N H bond. (1)
January 2022, AS Unit 2, Q24(d)(ii) (1 mark): Identify the bond responsible for the absorption at 1683 cm−1. . (1)
January 2022, AS Unit 3, Q2(d) (2 marks): The infrared spectrum of Y is shown. 0.8 0.6 Transmittance 0.4 0.2 4000 3000 2000 1000 Wavenumber / cm–1 The table shows some infrared absorption data. Wavenumb
January 2022, AS Unit 3, Q2(e)(i) (1 mark): Show that the mass spectrum is consistent with Y having the molecular formula C3H4O3 . (1)
January 2022, AS Unit 3, Q2(e)(ii) (1 mark): Suggest the structure of the ion causing the peak at m / z = 43 in the mass spectrum of Y. (1)
January 2022, Unit 5, Q5 (1 mark): The infrared spectrum of a compound X is shown. 100 90 80 70 60 % Transmittance 50 40 30 20 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber / cm−1 Which could
October 2021, AS Unit 2, Q1 (1 mark): The infrared spectrum of an organic compound is shown. 100 50 0 4000 3000 2000 1500 1000 500 Wavenumber / cm–1 Which of these compounds would give this infrared
October 2021, AS Unit 2, Q4 (1 mark): In a mass spectrum, the molecular ion is the ion which always has the A greatest abundance B greatest stability C highest charge D highest mass/charge ratio
October 2021, AS Unit 2, Q5 (1 mark): Butan-1-ol and butan-2-ol are isomers. Which m / z value would be expected to have a significant peak in the mass spectrum of butan-1-ol but not that of butan-2
October 2021, Unit 6, Q2(b)(i) (1 mark): Give the formula of one of the ions responsible for the peak at m / z = 29. (1)
October 2021, Unit 6, Q2(b)(ii) (1 mark): A contains one functional group. Give the m / z value of the molecular ion and the structure of A. (1) m / z value of the molecular ion structure of A
June 2021, AS Unit 2, Q12 (1 mark): Which could be the infrared spectrum of CH2=CHCH2OH? 100 A % Transmittance 50 0 4000 3000 2000 1500 1000 500 Wavenumber / cm–1 100 % Transmittance 50 B 0 4000 3
June 2021, AS Unit 2, Q13 (1 mark): The mass spectrum of propanone is shown. 100 80 60 Relative intensity 40 20 0 10 15 20 25 30 35 40 45 50 55 60 m / z Which fragment is most likely to produce th
June 2021, AS Unit 2, Q22(d) (2 marks): Use your Data Booklet to suggest the wavenumber of a strong absorbance you would expect to see in the infrared spectrum for phosgene. Justify your answer. (2)
June 2021, AS Unit 3, Q2(d)(i) (1 mark): Identify the wavenumber range and the bond responsible for one peak which you would expect to see in the infrared spectra of all three compounds. (1)
June 2021, AS Unit 3, Q2(d)(ii) (1 mark): Identify the wavenumber range and the bond responsible for one peak which you would expect to see in the infrared spectra of only one of the compounds. (1)
June 2021, AS Unit 3, Q2(d)(iii) (1 mark): Give a reason why there is a peak at m / z = 100 in the mass spectra of all three compounds. (1)
June 2021, AS Unit 3, Q2(d)(iv) (2 marks): Fragmentation of 1-methylcyclopentanol results in a significant peak at m / z = 85. Suggest the structures of the two species formed when one bond in 1-methylcy
June 2021, Unit 5, Q14 (1 mark): An aliphatic organic compound has the infrared spectrum shown. 100 P 50 Q 0 4000 3000 2000 1500 1000 500 Wavenumber / cm –1 What are the bond stretches responsi
June 2021, Unit 6, Q3(d)(iii) (1 mark): The mass spectrum of the compound is shown. 100 80 60 Relative intensity 40 20 0 0 10 20 30 40 50 60 70 80 90 m / z Deduce the relative molecular mass of the co
June 2021, Unit 6, Q3(d)(v) (2 marks): Determine the identity of the compound, using your answer to (d)(iv) and the fragmentation pattern of the mass spectrum. Justify your answer. (2) O O OH OH O B
January 2021, Unit 4, Q17(d)(iii) (1 mark): The infrared spectrum of E has an absorption in the range 1750 – 1735 cm−1. Name the functional group in E. (1)
October 2020, AS Unit 2, Q17(b)(iv) (3 marks): The infrared spectra of methanol and methanoic acid are shown. Explain how these could be used to show that all the methanol has been converted to methanoic aci
October 2020, AS Unit 3, Q3(a)(v) (1 mark): State whether or not it is possible to distinguish between F and G using infrared spectra. Justify your answer. Wavenumber values are not required. (1)
October 2020, Unit 6, Q2(a) (4 marks): Compound P is a colourless liquid with a sweet fruity smell. When a sample of P was heated with sodium hydroxide, a volatile product was formed which had a mole
January 2020, AS Unit 2, Q14(a) (1 mark): Which m / z peak would not be expected in the mass spectrum of propanone? (1) A 15 B 29 C 43 D 58
January 2020, AS Unit 2, Q17(d)(iii) (1 mark): Give the bond and the wavenumber range of its absorption in the infrared spectrum of 2-methylbutan-2-ol which would not be in the infrared spectrum of this chlo
June 2019, AS Unit 2, Q18 (1 mark): Which of these carboxylic acids would be expected to have a major peak at m / z = 57 in its mass spectrum? A CH3CH2CH2COOH B CH3COOH C (CH3)2CHCOOH D CH3CH2COOH
June 2019, AS Unit 2, Q22(b)(ii) (2 marks): Describe, by referring to wavenumbers and bonds, how the infrared spectra of the isomers differ from the infrared spectrum of alcohol Y. (2)
June 2019, AS Unit 3, Q2(d)(ii) (3 marks): The mass spectrum of C4H8Br2 had a pair of peaks at m / z = 107 and m / z = 109 and also peaks at m / z = 79 and m / z = 81 due to the isotopes of bromine. One

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