plumiAmount of substance: OCR A‑Level Chemistry A questions
Every OCR A-Level Chemistry A exam question on 2.1.3 Amount of substance, 2016–2025, with its mark scheme and examiner’s report.
Find questions1,820
Calculations
Q21(b)(ii)
The whole paper ↗
Q2(a)(ii)
The whole paper ↗![June 2025 Paper 3, question 2(a)(ii): What is the number of H atoms in 8.45 g of 2,3‑dimethylhexan‑1‑ol? Give your answer to 3 significant figures and in standard form. Number of H atoms = [3]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h43203-jun25-02-aii-qp.webp?v=3)
Q2(b)(ii)
The whole paper ↗
Q4(b)(i)
The whole paper ↗![June 2025 Paper 3, question 4(b)(i): What is the empirical formula of complex A? [1]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h43203-jun25-04-bi-qp.webp?v=3)
Q5(a)(ii)
The whole paper ↗
![June 2025 AS Paper 1, question 3: What is the number of hydrogen atoms in 6.8 g NH3? 2.408 × 1023 A 3.612 × 1023 B 7.224 × 1023 C 1.806 × 1024 D Your answer [1]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h03201-jun25-03-qp.webp?v=3)
Q21(d)(i)
The whole paper ↗![June 2025 AS Paper 1, question 21(d)(i): Calculate the concentration of HCl that the student used. Give your answer to 2 significant figures and in standard form. Concentration of HCl = mol dm–3 [3]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h03201-jun25-21-di-qp.webp?v=3)
Q25(c)
The whole paper ↗
Q2(b)(i)
The whole paper ↗![June 2025 AS Paper 2, question 2(b)(i): and pressure (RTP). Give your answer to 3 significant figures. Volume of gas cm3 [2]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h03202-jun25-02-bi-qp.webp?v=3)
Q2(b)(ii)
The whole paper ↗![June 2025 AS Paper 2, question 2(b)(ii): The volume of gas collected is less than the calculated volume. Suggest two reasons for this difference. 1 2 [2]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h03202-jun25-02-bii-qp.webp?v=3)
Q2(b)(iii)
The whole paper ↗![June 2025 AS Paper 2, question 2(b)(iii): Suggest one way in which the student could modify the apparatus to produce a volume closer to the calculated volume. [1]](https://pub-e8a9dbab8e2a4d089f52b2a45e0d0b50.r2.dev/bank/h03202-jun25-02-biii-qp.webp?v=3)
All 189 questions on Amount of substance, as a list
- June 2025, Paper 1, Q2 (1 mark): 11.895 g of hydrated cobalt(II) chloride, CoCl 2•xH2O, is heated to remove the water of crystallisation. After heating to constant mass, the mass of the anhydro
- June 2025, Paper 1, Q21(b)(ii) (4 marks): An iron(II) complex contains two different ligands: C5H5N, and Cl –. The complex has a molar mass of 442.8 g mol–1 and the following percentage composition by m
- June 2025, Paper 2, Q2 (1 mark): 0.0200 mol of the compound below reacts with Br2(aq) to make a saturated compound. How many grams of Br2 are needed for this reaction? Cl A 3.20 B 6.39 C 7.99 D
- June 2025, Paper 2, Q5 (1 mark): 0.200 mol of HOOCCH2CH2COOH is reacted with 0.300 mol NaOH. How many water molecules are formed? 1.204 × 1023 A 1.806 × 1023 B 2.408 × 1023 C 3.612 × 1023 D You
- June 2025, Paper 2, Q6 (1 mark): Propene can be prepared using the reactions shown. Which reaction has the lowest atom economy? A C3H7Br C3H6 + HBr B C12H26 2C3H6 + C6H14 C C8H18 C3H6 + C5H12 D
- June 2025, Paper 3, Q2(a)(ii) (3 marks): What is the number of H atoms in 8.45 g of 2,3‑dimethylhexan‑1‑ol? Give your answer to 3 significant figures and in standard form. Number of H atoms = [3]
- June 2025, Paper 3, Q2(b)(ii) (4 marks): The student uses the reaction of nuromol tablets with Na2CO3(aq) to determine the mass of ibuprofen and the mass of paracetomol in one nuromol tablet. The stude
- June 2025, Paper 3, Q4(b)(i) (1 mark): What is the empirical formula of complex A? [1]
- June 2025, Paper 3, Q5(a)(ii) (4 marks): Calculate the mass of LiAl H4 that the student should use in Step 2 and the percentage yield of pure C6H5CH2OH obtained in Step 4. Give the mass of LiAl H4 and
- June 2025, AS Paper 1, Q3 (1 mark): What is the number of hydrogen atoms in 6.8 g NH3? 2.408 × 1023 A 3.612 × 1023 B 7.224 × 1023 C 1.806 × 1024 D Your answer [1]
- June 2025, AS Paper 1, Q4 (1 mark): Which reaction to extract iron (Fe) has the highest atom economy? A 2Al + Fe2O3 2Fe + Al 2O3 B FeO + CO Fe + CO2 C Fe2O3 + 3CO 2Fe + 3CO2 D 2Fe2O3 + 3C 4Fe + 3C
- June 2025, AS Paper 1, Q5 (1 mark): Phosphorus is burnt in oxygen to produce a mixture of oxides. Which oxide has the closest to 50% by mass of phosphorus? A PO2 B P2O3 C P2O5 D P4O9 Your answer [
- June 2025, AS Paper 1, Q21(d)(i) (3 marks): Calculate the concentration of HCl that the student used. Give your answer to 2 significant figures and in standard form. Concentration of HCl = mol dm–3 [3]
- June 2025, AS Paper 1, Q25(c) (5 marks): 25.9 g of alcohol F is completely combusted in oxygen at a temperature of 100 °C and 1.50 × 105 Pa pressure. The equation for this reaction is: C4H10O + 6O2 4CO
- June 2025, AS Paper 2, Q2(b)(i) (2 marks): and pressure (RTP). Give your answer to 3 significant figures. Volume of gas cm3 [2]
- June 2025, AS Paper 2, Q2(b)(ii) (2 marks): The volume of gas collected is less than the calculated volume. Suggest two reasons for this difference. 1 2 [2]
- June 2025, AS Paper 2, Q2(b)(iii) (1 mark): Suggest one way in which the student could modify the apparatus to produce a volume closer to the calculated volume. [1]
- June 2024, Paper 1, Q3 (1 mark): Which chemical process is the most sustainable in terms of the atom economy of the iron produced? A Fe2O3 + 3CO 2Fe + 3CO2 B Fe2O3 + 3H2 2Fe + 3H2O C 2Fe2O3 4Fe
- June 2024, Paper 2, Q6 (1 mark): 4.30 g of the alcohol C5H9OH, (Mr = 86.0), is burned in oxygen. C5H9OH(l) + 7O2(g) 5CO2(g) + 5H2O(l) Which volume of oxygen gas is needed, in dm3, for this comp
- June 2024, Paper 2, Q10 (1 mark): 1.35 g of ethylamine gas, CH3CH2NH2 (Mr = 45.0), is reacted with 20 cm3 of 2.0 mol dm–3 hydrochloric acid forming a solution of ethylammonium chloride. +(aq) +
- June 2024, Paper 2, Q23(c) (3 marks): Calculate the percentage yield of compound H. Give your answer to three significant figures. percentage yield = % [3]
- June 2024, Paper 3, Q2(b)(ii) (3 marks): Determine the formula of compound A. formula of A = [3]
- June 2024, Paper 3, Q2(c)(iii) (2 marks): A research chemist synthesises two related compounds, compound C and compound D, from compound B. • In compound C, the N atoms in compound B had been replaced b
- June 2024, Paper 3, Q4(c)(ii) (2 marks): Calculate the percentage by mass of P in P3N3Cl 6. Give your answer to 2 decimal places. percentage by mass of P = % [2]
- June 2024, AS Paper 1, Q3 (1 mark): A nitrogen oxide contains 36.84% of nitrogen by mass. What is the empirical formula of the nitrogen oxide? A NO B NO2 C N2O D N2O3 Your answer [1]
- June 2024, AS Paper 1, Q4 (1 mark): Carbon monoxide reacts with oxygen to form carbon dioxide: 2CO(g) + O2(g) 2CO2(g) Which volumes of CO(g) and O2(g) produce the largest volume of CO2(g)? All gas
- June 2024, AS Paper 1, Q21(c) (3 marks): The iron compound, Fe(NO3)3, decomposes when heated. The equation for the decomposition of Fe(NO3)3 is shown below. 4Fe(NO3)3(s) 2Fe2O3(s) + 12NO2(g) + 3O2(g) M
- June 2024, AS Paper 2, Q1(d) (3 marks): A student heats 11.50 g of hydrated zinc sulfate, ZnSO4•7H2O, to remove all the water of crystallisation. Calculate the mass of anhydrous zinc sulfate that shou
- June 2024, AS Paper 2, Q2(b)(ii) (3 marks): A student plans to add 0.0100 mol of Ca to 120 cm3 of 0.100 mol dm–3 HCl (aq). When the student carries out this reaction, they are surprised that all the calci
- June 2024, AS Paper 2, Q4(b)(iii) (3 marks): The student uses 50.0 cm3 of H2O2 in the experiment. Equation 4.1 shows the reaction that takes place. 2H2O2(aq) 2H2O(l) + O2(g) Equation 4.1 Calculate the conc
- June 2023, Paper 1, Q1 (1 mark): Which sample contains the greatest number of molecules? A 35.0 g of C2H2 B 45.0 g of C2H6 C 60.0 g of C4H10 D 100.0 g of C6H6 Your answer [1]
- June 2023, Paper 1, Q2 (1 mark): 0.688 g of an oxide of manganese is reduced by hydrogen gas to form manganese metal and 0.235 g of water. What is the formula of the oxide of manganese? A MnO B
- June 2023, Paper 1, Q3 (1 mark): How many hydrogen atoms are in 2.50 g of pharmacolite, CaHAsO4•2H2O (Mr = 216.0)? 6.97 × 1021 A 2.09 × 1022 B 2.79 × 1022 C 3.48 × 1022 D Your answer [1]
- June 2023, Paper 1, Q4 (1 mark): 40.0 cm3 of 0.200 mol dm–3 HCl is added to 60.0 cm3 of 0.100 mol dm–3 NaOH. 4 What is the concentration of the resulting solution? 0.0200 mol dm–3 HCl and 0.020
- June 2023, Paper 1, Q19(b) (5 marks): N2O4 reacts fully with oxygen to form a different oxide of nitrogen, oxide A, as the only product. Oxide A is collected and cooled to 75.0 °C at a pressure of 1
- June 2023, Paper 1, Q20(c)(ii) (2 marks): The student then reacts 1.00 g of calcium carbonate, CaCO3, with an excess of dilute nitric acid, HNO3. Explain why the student’s two reactions produce differen
- June 2023, Paper 2, Q8 (1 mark): For complete combustion, 0.100 mol of an alkane requires 22.8 dm3 of O2, measured at RTP. 8 Which alkane has undergone complete combustion? A pentane B hexane C
- June 2023, Paper 2, Q16(b)(iii) (3 marks): Organic compound B is formed by the substitution of some of the 14 H atoms in 2-methylpentane by Br atoms. 0.8649 g of compound B is heated until it is vaporise
- June 2023, Paper 2, Q18(b) (3 marks): Determine the percentage yield of 1,3-dinitrobenzene. Give your answer to 3 significant figures. percentage yield = % [3]
- June 2023, Paper 2, Q20(b)(ii) (3 marks): For the treatment of TB, the maximum daily dosage of PAS that should be prescribed is 300 mg per kg of body mass. A child weighs 20.0 kg. Calculate the number o
- June 2023, Paper 3, Q1(h) (1 mark): The element with an average atomic mass of 1.244 × 10–22 g. [1]
- June 2023, Paper 3, Q4(b)(i) (2 marks): What masses are needed of ammonium sulfate and CuSO4 • 5H2O? mass of ammonium sulfate g mass of CuSO4 • 5H2O g [2]
- June 2023, Paper 3, Q4(b)(ii) (1 mark): In Step 3, why does the student allow the solvent to evaporate and not boil off all the solvent in Step 2? [1]
- June 2023, Paper 3, Q6(e) (6 marks): This question is about nitric acid, hydrochloric acid and sulfuric acid. (e)* Three reactions involving sulfuric acid are shown below. Reaction 1 Dilute sulfuri
- June 2023, AS Paper 1, Q2 (1 mark): A hydrocarbon contains 85.71% carbon by mass. What is the empirical formula of the hydrocarbon? A CH B CH2 C CH4 D C2H4 Your answer [1]
- June 2023, AS Paper 1, Q3 (1 mark): Hydrogen can be prepared industrially by the reaction of methane with steam. The equation is shown below. CH4(g) + 2H2O(g) 4H2(g) + CO2(g) What is the atom econ
- June 2023, AS Paper 1, Q7 (1 mark): How many oxygen atoms are in 120.2 g of SiO2? 3.01 × 1023 A 1.20 × 1024 B 2.41 × 1024 C 3.61 × 1024 D Your answer [1]
- June 2023, AS Paper 1, Q8 (1 mark): Magnesium nitrate, Mg(NO3)2, decomposes when heated: Mg(NO3)2(s) MgO(s) + 2NO2(g) + ½O2(g) 0.00250 mol of Mg(NO3)2 is decomposed. What is the volume of gas prod
- June 2023, AS Paper 1, Q9 (1 mark): Zinc reacts with aqueous silver nitrate, as shown in the equation: Zn(s) + 2AgNO3(aq) 2Ag(s) + Zn(NO3)2(aq) 0.10 g of zinc is added to 15 cm3 of 0.25 mol dm–3 a
- June 2023, AS Paper 1, Q10 (1 mark): 15.00 cm3 of 18.0 mol dm–3 concentrated hydrochloric acid is diluted with water to prepare 250 cm3 of dilute hydrochloric acid. What is the concentration, in mo
- June 2023, AS Paper 2, Q1(b)(ii) (4 marks): In Reaction 1.2, the percentage yield of titanium from TiCl4 is 72.0%. Calculate the minimum mass, in kg, of sodium that is needed to produce 1.00 kg of titaniu
- June 2023, AS Paper 2, Q2(b)(ii) (4 marks): The student obtains 3.28 g of precipitate. Calculate the percentage by mass of NaCl (s) in the 5.00 g mixture. Give your answer to 3 significant figures. percen
- June 2023, AS Paper 2, Q3(a) (6 marks): This question is about halogens and halogen compounds. (a)* Seawater contains very small quantities of dissolved iodide ions. The concentration of potassium iod
- June 2022, Paper 1, Q2 (1 mark): cm3 of nitrogen gas reacts with 10 cm3 of oxygen gas to form 20 cm3 of a gaseous product. 2 Which equation is the most likely for the reaction? A N2(g) + O2(g)
- June 2022, Paper 1, Q3 (1 mark): 0.541 g of an element X is reacted with oxygen to form 0.790 g of the oxide X2O3. What is the element X? A Al B Cr C Ga D Sc Your answer [1]
- June 2022, Paper 1, Q5 (1 mark): The mass of 4 molecules of a substance is 2.125 × 10–22 g. 5 What is the possible formula of the substance? A CH4 B O2 C SO2 D I2 Your answer [1]
- June 2022, Paper 1, Q21(c)(i) (3 marks): A typical sample of limestone contains 95.0% by mass of calcium carbonate, CaCO3. Fertiliser Z, Ca5NH4(NO3)11•10H2O (Mr = 1080.5 g mol–1) can be made from limes
- June 2022, Paper 2, Q6 (1 mark): Which process has the highest atom economy for preparing ethene, C2H4? In each process, assume that ethene is the only product that is used. A C10H22 3C2H4 + C4
- June 2022, Paper 2, Q7 (1 mark): Complete combustion of 0.050 mol of an alkane produces 5.40 g of H2O. What is the molecular formula of the alkane? A C2H6 B C3H8 C C4H10 D C5H12 Your answer [1]
- June 2022, Paper 2, Q8 (1 mark): The structure of the painkiller, paracetamol, is shown below. OH O N H paracetamol A tablet contains 3.31 × 10–3 mol of paracetamol. What is the mass of paracet
- June 2022, Paper 2, Q9 (1 mark): The compound below reacts with hydrogen gas to form a saturated compound. CN What is the volume of hydrogen, measured at room temperature and pressure, that rea
- June 2022, Paper 2, Q17 (6 marks): 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 C
- June 2022, Paper 2, Q18(b) (4 marks): A student is provided with two unknown carbonyl compounds, F and G. The compounds are analysed and found to have identical percentage compositions by mass: C: 6
- June 2022, Paper 3, Q2(a)(i) (3 marks): 420 dm3 of chlorine, measured at RTP, is reacted with an excess of Ca(OH)2. The solid products are dissolved in water to form 4.00 m3 of solution. Calculate the
- June 2022, Paper 3, Q3(a) (6 marks): Information about 1-bromobutane and butan-1-ol is shown in the table. Density / g cm–3 Compound Melting point / °C Boiling point / °C 1-bromobutane –113 102 1.2
- June 2022, AS Paper 1, Q7 (1 mark): A sample of lead(II) sulfate (M = 303.3 g mol–1) is decomposed by heat, as shown in the equation 7 below. 2PbSO4(s) → 2PbSO3(s) + O2(g) The reaction forms 2.40
- June 2022, AS Paper 1, Q8 (1 mark): Which volume of 18.0 mol dm–3 hydrochloric acid should be diluted to 250.0 cm3 to prepare a 8 0.450 mol dm–3 solution of hydrochloric acid? 4.50 cm3 A 6.25 cm3
- June 2022, AS Paper 1, Q9 (1 mark): What is the number of ions in 4.00 mol of magnesium chloride, MgCl2? 1.81 × 1024 A 2.41 × 1024 B 4.82 × 1024 C 7.22 × 1024 D Your answer [1]
- June 2022, AS Paper 1, Q16 (1 mark): Complete combustion of an alkane forms 30 cm3 of carbon dioxide and 40 cm3 of water vapour, under the same conditions of temperature and pressure. Which alkane
- June 2022, AS Paper 1, Q22(c) (3 marks): Substance A is a hydrated salt with the following percentage composition by mass: Zn, 21.99%; H, 4.04%; N, 9.41%; O, 64.56%. • Determine the empirical formula o
- June 2022, AS Paper 1, Q26(b) (5 marks): A bromoalkane D is a liquid at room temperature and pressure but can easily be vaporised. When vaporised, 0.330 g of D produces 74.0 cm3 of gas at 1.01 × 105 Pa
- June 2022, AS Paper 2, Q5(b) (2 marks): 2-Bromobutane can also be prepared by reacting but-2-ene, CH3CH=CHCH3, with hydrogen bromide, HBr (Reaction 5.2). CH3CH=CHCH3 + HBr CH3CH2CHBrCH3 Reaction 5.2 E
- June 2022, AS Paper 2, Q5(c)(i) (3 marks): A student plans to prepare 10.0 g of 2-bromobutane using Reaction 5.3. The percentage yield is 67.0%. Calculate the mass of CH3CH2CHOHCH3 needed for this prepar
- November 2021, Paper 1, Q4 (1 mark): Which sample contains the greatest number of molecules? A 140.0 g C2H2 B 180.0 g C2H6 C 240.0 g C4H10 D 400.0 g C6H6 Your answer [1]
- November 2021, Paper 1, Q5 (1 mark): Chromium(III) oxide, Cr2O3, is reduced to chromium by heating with magnesium. 5 What is the minimum mass of Mg required to reduce 11.4 g of chromium(III) oxide?
- November 2021, Paper 1, Q6 (1 mark): A student is supplied with 100.0 cm3 of a solution of 0.400 mol dm–3 magnesium iodide, MgI2. 6 A student plans to dilute this solution so that the iodide concen
- November 2021, Paper 1, Q22(b)(i) (2 marks): Show that NaOH is in excess. [2]
- November 2021, Paper 2, Q3 (1 mark): Which sample contains the greatest number of carbon atoms? A 20.0 g C6H5OH B 30.0 g C2H5COOH C 40.0 g CH3CHO D 50.0 g CH3OH Your answer [1]
- November 2021, Paper 2, Q18(c)(ii) (3 marks): One ibuprofen tablet contains 400 mg of ibuprofen. Calculate the number of ibuprofen molecules in one ibuprofen tablet. Give your answer to 3 significant figure
- November 2021, Paper 3, Q1(d) (4 marks): Compound A has the following percentage composition by mass: Ca, 81.10%; N, 18.90%. A student reacts compound A with water to form alkaline gas B and alkali C.
- November 2021, Paper 3, Q2(a) (2 marks): Draw a labelled diagram of suitable apparatus for this investigation. [2]
- November 2021, Paper 3, Q2(b) (3 marks): Analyse the student’s results to conclude which of Equation 1 or 2 or 3, is supported by the experimental results. Assume that the conditions in the laboratory
- November 2021, Paper 3, Q2(c) (2 marks): The student repeats the experiment but adds concentrated hydrochloric acid instead of dilute hydrochloric acid. The apparatus gets hot during the reaction. Pred
- November 2021, Paper 3, Q2(d) (2 marks): The student modifies their method as outlined below: • 1.52 g (0.01 mol) of europium is reacted with an excess of dilute hydrochloric acid. • An excess of aqueo
- November 2021, Paper 3, Q5(a)(ii) (5 marks): A 16.0 dm3 airbag is inflated at 17.0 ºC. The pressure in the inflated airbag is 1.20 × 105 Pa. Calculate the mass of NaN3 that has decomposed. Give your answer
- November 2021, Paper 3, Q5(c) (6 marks): This question is about nitrogen and its compounds. (c)* This question is about two reactions of ammonia. Reaction 1 Excess ammonia is reacted with 4.77 g of cop
- November 2021, AS Paper 1, Q4 (1 mark): Which alkane is 82.8% carbon by mass? A CH4 B C2H6 C C4H10 D C8H18 Your answer [1]
- November 2021, AS Paper 1, Q5 (1 mark): Which gas sample has the greatest mass at RTP? 50 cm3 of Ar(g) A 100 cm3 of O2(g) B 150 cm3 of N2(g) C 200 cm3 of Ne(g) D Your answer [1]
- November 2021, AS Paper 1, Q6 (1 mark): A student mixes 250.0 cm3 of 0.100 mol dm–3 KOH with 750.0 cm3 of 0.100 mol dm–3 Ca(OH)2. 6 What is the OH– concentration, in mol dm–3, in the resulting mixture
- November 2021, AS Paper 1, Q21(d)(ii) (2 marks): What is the number of fluorine atoms in 7.896 g of halothane, C2HBrCl F3? number of fluorine atoms = [2]
- November 2021, AS Paper 1, Q25(a)(i) (2 marks): Determine the empirical formula of the scandium oxide. empirical formula = [2]
- November 2021, AS Paper 1, Q25(a)(ii) (1 mark): The student was unsure that all of the scandium had reacted. Suggest one modification that the student could make to their method to be confident that all the s
- November 2021, AS Paper 1, Q25(b) (5 marks): A gas cylinder has a gas volume of 9.39 dm3. The gas cylinder holds 1.69 kg of a gas at a pressure of 1.37 × 107 Pa at 20 °C. Determine the molar mass and possi
- November 2021, AS Paper 2, Q6(c)(i) (2 marks): Calculate the mass of barium that the student uses. Give your answer to 2 decimal places. mass of barium = g [2]
- November 2020, Paper 1, Q2 (1 mark): Which statement gives the numerical value of the Avogadro constant? A The number of moles in 12 g of carbon-12. B The number of electrons lost by 20.05 g of cal
- November 2020, Paper 1, Q3 (1 mark): 0.80 g of element X is reacted with 0.40 g of O2 to form an oxide with the formula X2O3. What is the identity of element X? A Aluminium B Titanium C Germanium D
- November 2020, Paper 1, Q16(b)(ii) (3 marks): Calculate the total number of ions in 1.74 g of magnesium bromide, MgBr2. Give your answer to 3 significant figures. number of ions = [3]
- November 2020, Paper 1, Q21(c) (3 marks): Compound A contains bromine and fluorine only, and has a boiling point of 41 °C. 1.26 g of compound A is heated to 80 °C. The volume of gas produced is 0.209 dm
- November 2020, Paper 1, Q22(b)(i) (3 marks): Calculate the values of x and y in the formula of compound J. x = y = [3]
- November 2020, Paper 2, Q11 (1 mark): Complete combustion of 1.00 g of a hydrocarbon gives 3.38 g carbon dioxide. What is the empirical formula of the hydrocarbon? A CH B CH2 C C2H5 D C3H8 Your answ
- November 2020, Paper 2, Q20(a) (6 marks): Cyclopentanol can be reacted to form cyclopentene. Cyclopentene is a liquid with a boiling point of 44 °C and a density of 0.74 g cm−3. A student plans to prepa
- November 2020, Paper 2, Q21(b)(iii) (3 marks): Some people are concerned that aspartame, C14H18N2O5, may have adverse health effects. Research shows that the safe maximum daily intake of aspartame is 1.7 × 1
- November 2020, Paper 3, Q1(b)(ii) (6 marks): Amine A is a liquid at room temperature and pressure. When vaporised, 0.202 g of the amine produces 72.0 cm3 of gas at 1.00 × 105 Pa and 100 °C. The 13C NMR spe
- November 2020, Paper 3, Q4(b)(i) (1 mark): Calculate the amount, in mol, of CO2 released in the reaction. Amount of CO2 = mol [1]
- November 2020, Paper 3, Q4(b)(ii) (3 marks): Calculate the molar mass of X2CO3 and identify metal X. Molar mass of X2CO3 = g mol−1 Metal X = [3]
- November 2020, Paper 3, Q4(c)(i) (1 mark): The student wondered whether the reaction was complete when the mass was recorded after 5 minutes (Step 3). How could the student modify the experimental proced
- November 2020, Paper 3, Q4(c)(ii) (2 marks): The student finds out that carbon dioxide is slightly soluble in water. State and explain how the solubility of CO2 would affect the calculated molar mass of X2
- November 2020, AS Paper 1, Q9 (1 mark): 2.0 dm3 of Cl 2 gas reacts with 2.0 dm3 of Cl F3 gas to form 6.0 dm3 of a gaseous compound. 9 The reaction has 100% atom economy and all volumes are measured at
- November 2020, AS Paper 1, Q10 (1 mark): Which sample contains the greatest number of molecules? A 1 g of methanol, CH3OH B 2 g of nitrogen dioxide, NO2 C 3 g of phosphorus, P4 D 4 g of iodine, I2 Your
- November 2020, AS Paper 1, Q18 (1 mark): A student reacts 24.24 g of 2-bromobutane in the reaction below. CH3CH2CHBrCH3 + NaOH → CH3CH2CHOHCH3 + NaBr Mr = 136.9 Mr = 74.0 The reaction produces 4.81 g o
- November 2020, AS Paper 1, Q22(c) (5 marks): Bromine reacts with fluorine to form compound A. Compound A is a liquid at room temperature and pressure but can easily be vaporised. When vaporised, 0.428 g of
- November 2020, AS Paper 1, Q23(a) (3 marks): Barium hydroxide is an alkali which releases hydroxide ions, OH−, in aqueous solution. A barium hydroxide solution contains 3.89 g of Ba(OH)2 in 100 cm3 at 20 °
- November 2020, AS Paper 2, Q1(b)(i) (3 marks): Calculate the minimum volume, in cm3, of 0.150 mol dm–3 HCl (aq) that the student needs for the reaction. Give your answer to 3 significant figures. minimum vol
- November 2020, AS Paper 2, Q1(b)(ii) (1 mark): Calculate the volume of H2(g), in cm3, that would be produced at RTP. volume of H2(g) = cm3 [1]
- November 2020, AS Paper 2, Q1(b)(iii) (2 marks): The student repeats the experiment with 0.192 g of magnesium instead of nickel, using the same volume of 0.150 mol dm–3 HCl (aq) as in (b)(i). State and explain
- November 2020, AS Paper 2, Q5(d)(i) (2 marks): Calculate the atom economy for the preparation of alcohol A in equation 5.1. atom economy = % [2]
- June 2019, Paper 1, Q3 (1 mark): One molecule of a gas has a mass of 2.658 × 10−23 g. 3 What is a possible formula of the gas? A CH4 B O2 C SO2 D SO3 Your answer [1]
- June 2019, Paper 1, Q4 (1 mark): In the laboratory, acid spills can be cleaned up and made safe by spreading anhydrous sodium carbonate over the spill to neutralise the acid. A student accident
- June 2019, Paper 1, Q8 (1 mark): 3.528 g of a Group 2 metal, M, is reacted with an excess of chlorine. The reaction forms 9.775 g of a chloride. What is metal M? A magnesium B calcium C stronti
- June 2019, Paper 1, Q18(c)(iii) (1 mark): Some iron supplements contain iron(II) sulfate or iron(II) fumarate. The information in Table 18.3 is taken from the labels of two iron supplements, A and B. Ma
- June 2019, Paper 2, Q11 (1 mark): A student reacts 4.50 g of C6H5NH2 with excess CH3COCl in the reaction below. C6H5NH2 + CH3COCl → C6H5NHCOCH3 + HCl Mr = 93.0 Mr = 135.0 The reaction produces 3
- June 2019, Paper 3, Q1(d) (2 marks): What mass of carbon dioxide (in g) is formed by the complete combustion of 42.0 m3 (measured at RTP) of propane? mass = g [2]
- June 2019, Paper 3, Q1(f) (2 marks): What is the number of oxygen atoms in 4.26 g of P2O5? number of oxygen atoms = [2]
- June 2019, Paper 3, Q2(d) (3 marks): Calculate the percentage yield of benzoic acid. Give your answer to 3 significant figures. percentage yield = % [3]
- June 2019, Paper 3, Q3(a)(ii) (1 mark): The student uses safety glasses and a lab coat. State, with a reason, one other important safety precaution the student should take when carrying out this exper
- June 2019, Paper 3, Q3(a)(iii) (2 marks): The student was not sure that all the oxygen had been removed from the lead oxide. Suggest two modifications that the student could make to their method to be c
- June 2019, Paper 3, Q3(a)(iv) (2 marks): The student makes suitable modifications to the method and repeats the experiment to obtain the accurate results shown below. Mass of dish / g 8.364 Mass of dis
- June 2019, Paper 3, Q6(b) (6 marks): This question is about reactions of iron compounds. (b)* Compound C is a hydrated ionic compound with the empirical formula: FeH18N3O18. A student investigates
- June 2019, AS Paper 1, Q3 (1 mark): What is the percentage composition by mass of nitrogen in (NH4)2CO3? A 14.58% B 17.95% C 29.17% D 37.50% Your answer [1]
- June 2019, AS Paper 1, Q4 (1 mark): Which chemical process is the most sustainable in terms of the atom economy of the organic product? A CO2 + 3H2 → CH3OH + H2O B CH3CH2OH + NaCl + H2SO4 → CH3CH2
- June 2019, AS Paper 1, Q5 (1 mark): 8.0 dm3 of NO is mixed with 6.0 dm3 of O2 at room temperature and pressure (RTP). 5 The reaction below takes place until one of the reactants is used up. 2NO(g)
- June 2019, AS Paper 1, Q6 (1 mark): What is the volume of 0.0100 mol of N2 at 350 °C and 200 kPa? 145 cm3 A 259 cm3 B 145 dm3 C 259 dm3 D Your answer [1]
- June 2019, AS Paper 1, Q7 (1 mark): 0.24 g of an element, X, is reacted with 0.0100 mol Cl 2 to form a chloride with the formula XCl 2. What is element X? A carbon B magnesium C molybdenum D titan
- June 2019, AS Paper 1, Q25(b)(iii) (3 marks): Organic compound E is formed by the substitution of some of the H atoms in butane by Cl atoms. A chemist found that 0.636 g of compound E has a volume of 78.0 c
- June 2019, AS Paper 2, Q1(d)(i) (3 marks): Calculate the value of x in SrCl2•xH2O. Give your answer to 2 significant figures. x = [3]
- June 2019, AS Paper 2, Q1(d)(ii) (1 mark): Suggest why the student takes four readings of the mass of the crucible and residue. [1]
- June 2019, AS Paper 2, Q1(d)(iii) (2 marks): Suggest two modifications to the method that would reduce the percentage uncertainty in the mass of the residue. 1 2 [2]
- June 2019, AS Paper 2, Q2(b) (3 marks): A solution of magnesium nitrate can be prepared by reacting magnesium carbonate, MgCO3, with nitric acid, HNO3(aq). The equation is shown below. MgCO3(s) + 2HNO
- June 2019, AS Paper 2, Q4(a) (3 marks): The student plans to react 50.0 cm3 of 0.100 mol dm–3 HCl with 0.200 g of zinc (an excess). Calculate the volume, in cm3, of hydrogen that should be produced at
- June 2018, Paper 1, Q3 (1 mark): What is the number of hydrogen atoms in 0.125 mol of C2H5OH? 7.525 × 1022 A B 4.515 × 1023 3.7625 × 1023 C D 3.612 × 1024 Your answer [1]
- June 2018, Paper 1, Q20(c) (4 marks): Compound A is an oxide of chlorine that is a liquid at room temperature and pressure and has a boiling point of 83 °C. When 0.4485 g of A is heated to 100 °C at
- June 2018, Paper 2, Q7 (1 mark): Ethanol can be prepared by different reactions. Which reaction has the lowest atom economy? A C6H12O6 → 2C2H5OH + 2CO2 B C2H4 + H2O → C2H5OH C C2H5Br + H2O → C2
- June 2018, Paper 2, Q22(c)(i) (5 marks): Compound N is a fuel additive containing carbon, hydrogen and oxygen only. Complete combustion of 1.71 g of compound N produces 2.97 g of CO2 and 1.62 g of H2O.
- June 2018, Paper 3, Q1(a)(vi) (1 mark): The element X, which forms a compound with hydrogen, XH3, with a molar mass of 34.0 g mol–1. [1]
- June 2018, Paper 3, Q1(a)(viii) (1 mark): The element which has a density of 1.33 × 10–3 g cm–3 at room temperature and pressure. [1]
- June 2018, Paper 3, Q2(a)(ii) (3 marks): The student allows the reaction in equation 2.1 to proceed until no more gas is evolved. The volume of O2 in the syringe is now 55 cm3, measured at RTP. Calcula
- June 2018, AS Paper 1, Q2 (1 mark): What is the number of oxygen atoms in 88.0 g of CO2? 3.01 × 1023 A 1.20 × 1024 B 2.41 × 1024 C 4.82 × 1024 D Your answer [1]
- June 2018, AS Paper 1, Q3 (1 mark): A compound has the composition by mass: H, 5.00%; N, 35.00%; O, 60.00%. Which compound has this composition? A HNO3 B NH4NO3 C HNO2 D NH2OH Your answer [1]
- June 2018, AS Paper 1, Q4 (1 mark): Sodium reacts with water as shown below. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) Which mass of sodium reacts with water to produce 960 cm3 of hydrogen gas at RTP?
- June 2018, AS Paper 1, Q22(a)(ii) (3 marks): The student plans to add magnesium to 50.0 cm3 of 1.24 mol dm−3 H3PO4. Calculate the mass of magnesium that the student should add to react exactly with the pho
- June 2018, AS Paper 1, Q22(b)(i) (4 marks): 3.20 × 10−2 mol of H3PO3 is completely decomposed by this reaction. Calculate the volume of phosphine gas formed, in cm3, at 100 kPa pressure and 200 °C. volume
- June 2018, AS Paper 2, Q5(a)(ii) (2 marks): The student used 0.150 mol of butan-1-ol. The student obtained a 61.4% percentage yield of 1-bromobutane. Calculate the mass of 1-bromobutane obtained. Give you
- June 2017, Paper 1, Q4 (1 mark): Which calcium compound contains the greatest percentage by mass of calcium? A calcium carbonate B calcium nitrate C calcium hydroxide D calcium sulfate Your ans
- June 2017, Paper 1, Q5 (1 mark): 0.0200 mol of calcium oxide is reacted completely with 2.00 mol dm–3 HCl. 5 What is the volume, in cm3, of 2.00 mol dm–3 HCl required for this reaction? A 15 B
- June 2017, Paper 1, Q6 (1 mark): How many electrons are removed from 2.02 × 10–2 g of Ne(g) atoms to form Ne+(g) ions? 6 3.36 × 10–26 A 1.66 × 10–27 B 6.02 × 1020 C 1.22 × 1022 D Your answer [1
- June 2017, Paper 1, Q7 (1 mark): Silicon can be made by heating silicon tetrachloride, SiCl 4, with zinc. SiCl 4 + 2Zn Si + 2ZnCl 2 8.50 g of SiCl 4 is reacted with an excess of zinc. The perce
- June 2017, Paper 1, Q12 (1 mark): HA and HB are two strong monobasic acids. 25.0 cm3 of 6.0 mol dm–3 HA is mixed with 45.0 cm3 of 3.0 mol dm–3 HB. What is the H+(aq) concentration, in mol dm–3,
- June 2017, Paper 1, Q19(a) (3 marks): Determine the total volume of oxygen, measured at room temperature and pressure, that the student should be prepared to collect in this investigation. Suggest a
- June 2017, Paper 1, Q23(b) (6 marks): This question is about reactions of ions and compounds of transition elements. (b)* A hydrated nickel(II) complex, A, is heated in a crucible to remove the wate
- June 2017, Paper 2, Q3 (1 mark): Complete combustion of an organic compound forms 40 cm3 of carbon dioxide and 40 cm3 of 3 water vapour, under the same conditions of temperature and pressure. W
- June 2017, Paper 2, Q5 (1 mark): Which type of reaction has the greatest atom economy? A Substitution B Hydrolysis C Elimination D Addition Your answer [1]
- June 2017, Paper 2, Q12 (1 mark): 0.1 mol of HOOCCH2COOH are reacted with 0.1 mol of aqueous NaOH. How many molecules of water are formed? 6.02 × 1022 A 3.01 × 1022 B 6.02 × 1023 C 3.01 × 1023 D
- June 2017, Paper 2, Q16(e)(i) (2 marks): Reaction of 204 mg of myrcene with hydrogen gas produces a saturated alkane. Calculate the volume of hydrogen gas, in cm3 and measured at RTP, needed for this r
- June 2017, Paper 2, Q16(e)(ii) (4 marks): β-Carotene is a naturally occurring unsaturated hydrocarbon found in carrots. A β-carotene molecule contains 40 carbon atoms, has two rings, and a branched chai
- June 2017, Paper 2, Q17(a)(ii) (6 marks): This question is about the chemistry of aromatic compounds. (ii)* A chemist carries out the reaction in Equation 17.1 using 4.97 g of benzoic acid. The chemist
- June 2017, Paper 2, Q20(a) (3 marks): The percentage composition and mass spectrum of the compound are shown below. Percentage composition by mass: C, 70.58%; H, 5.92%; O, 23.50%. Mass spectrum 100
- June 2017, Paper 3, Q1(c) (2 marks): Determine the formula of ‘methane hydrate’, CH4•xH2O. In the formula, show the value of x to two decimal places. formula = [2]
- June 2017, Paper 3, Q1(d) (4 marks): Calculate the volume of methane, in dm3, that would be released from the melting of each 1.00 kg of ‘methane hydrate’ at 101 kPa and 0 °C. Give your answer to t
- June 2017, Paper 3, Q4(c)(ii) (2 marks): A typical tablet of chromium(III) picolinate contains 200 μg of chromium. Calculate the mass, in g, of chromium(III) picolinate in a typical tablet. 1 μg = 10−6
- June 2017, AS Paper 1, Q2 (1 mark): An organic compound has the composition by mass: C, 53.33 %; H, 11.11%; O, 35.56%. What is the empirical formula of the organic compound? A C4H8O2 B C4H10O2 C C
- June 2017, AS Paper 1, Q3 (1 mark): Samples of four hydrocarbons are completely burnt under the same conditions of temperature and pressure. Which sample produces the greatest volume of CO2? A 0.4
- June 2017, AS Paper 1, Q4 (1 mark): Which reaction produces the smallest atom economy of BaCl2? A BaCl2•2H2O → BaCl2 + 2H2O B BaO + 2HCl → BaCl2 + H2O C BaCO3 + 2HCl → BaCl 2 + CO2 + H2O D Ba + 2H
- June 2017, AS Paper 1, Q25(b) (5 marks): An alkene D is a liquid at room temperature and pressure but can easily be vaporised. When vaporised, 0.1881 g of D produces 82.5 cm3 of gas at 101 kPa and 373
- June 2017, AS Paper 2, Q1(a)(iii) (2 marks): Calculate the number of barium ions in 1.50 g of barium oxide. Give your answer in standard form and to three significant figures. number of barium ions = [2]
- June 2017, AS Paper 2, Q1(b)(iii) (2 marks): Hydrated barium chloride can be crystallised from solution. Hydrated barium chloride has the formula BaCl2•xH2O and a molar mass of 244.3 g mol −1. Determine th
- June 2017, AS Paper 2, Q6(a)(ii) (3 marks): The student carries out this synthesis and obtains 1.23 g of pure cyclohexene from 5.50 g of bromocyclohexane. Calculate the percentage yield of cyclohexene. Gi
- June 2016, AS Paper 1, Q3 (1 mark): Calcium nitrate, Ca(NO3)2, decomposes when heated, as shown below. Ca(NO3)2(s) → CaO(s) + 2NO2(g) + ½O2(g) A student decomposes 0.00500 mol of Ca(NO3)2 and coll
- June 2016, AS Paper 1, Q21(b)(ii) (2 marks): One coin has a mass of 5.00 g and contains 84.0% of copper, by mass. Calculate the number of copper atoms in one coin. Give your answer in standard form and to
- June 2016, AS Paper 1, Q22(a) (3 marks): A hydrated salt, compound A, is analysed and has the following percentage composition by mass: Cr, 19.51%; Cl, 39.96%; H, 4.51%; O, 36.02%. Calculate the formul
- June 2016, AS Paper 1, Q22(b)(i) (1 mark): The maximum error in each mass measurement using the balance is ±0.005 g. Calculate the percentage error in the mass of water removed. percentage error = % [1]
- June 2016, AS Paper 1, Q22(b)(ii) (1 mark): Suggest one modification that the student could make to their method to reduce the percentage error in the mass of water removed. [1]
- June 2016, AS Paper 1, Q22(b)(iii) (1 mark): The student is not sure that all the water of crystallisation has been removed. How could the student modify the experiment to be confident that all the water o
- June 2016, AS Paper 1, Q24(c) (2 marks): The 50.0 cm3 of KI(aq) used in the experiment contains 10% more KI than is needed to react with 50.0 cm3 of 1.50 mol dm–3 Pb(NO3)2(aq). Pb(NO3)2(aq) + 2KI(aq) →
- June 2016, AS Paper 1, Q26(c)(i) (1 mark): What is the empirical formula of compound F? [1]
- June 2016, AS Paper 2, Q1(c)(ii) (3 marks): Identify the Group 2 metal, M. Show your working. Group 2 metal = [3]
- June 2016, AS Paper 2, Q1(d) (1 mark): The student plans to repeat the experiment using the same mass of a Group 2 metal from further down the group. Predict whether the volume of hydrogen produced w
- June 2016, AS Paper 2, Q4(b) (4 marks): N2O is supplied as a compressed gas in steel cylinders for use as an anaesthetic. The cylinders are stored at 20.0 °C. Calculate the gas pressure, in Pa, in a 2
- June 2016, AS Paper 2, Q5(a)(ii) (3 marks): An excess of strontium carbonate, SrCO3, is mixed with 20.0 cm3 of 1.25 mol dm–3 nitric acid, HNO3. Calculate the mass of SrCO3 that reacts with the HNO3. mass
- June 2016, AS Paper 2, Q6(d) (3 marks): 20.2 g of butan-2-ol is reacted with excess sodium bromide and sulfuric acid. CH3CH(OH)CH2CH3 + NaBr + H2SO4 CH3CHBrCH2CH3 + NaHSO4 + H2O 25.2 g of CH3CHBrCH2CH
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? Every OCR A-Level Chemistry A paper, or our free OCR-style practice pack.
Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.