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Practical techniques and apparatus (PAGs)

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 · 42 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · Paper 1 · Q20(a)(i) · 4 marks ·
20 Standard electrode potentials for seven redox systems are shown in the table below. Redox Half-equation Eɵ / V system 1 V2+(aq) + 2e– V(s) –1.18 2 Zn2+(aq) + 2e– Zn(s) –0.76 3 Co2+(aq) + 2e– Co(s) –0.28 4 V3+(aq) + e– V2+(aq) –0.26 5 2H+(aq) + VO2+(aq) + e– V3+(aq) + H2O(l) +0.34 6 Ag+(aq) + e– Ag(s) +0.80 7 2H+(aq) + VO2 +(aq) + e– VO2+(aq) + H2O(l) +1.00 (a) (i) A student sets up a standard cell based on redox systems 2 and 4. Draw a labelled diagram to show how this cell could be set up to measure its standard cell potential. Include the conditions required to measure the standard cell potential. standard conditions .......................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [4]
2. June 2025 · AS Paper 2 · Q3(a)(i) · 1 marks ·
3 Malic acid tablets are sold as a health supplement. A student carries out a titration to determine the mass of malic acid, C4H6O5, in one tablet. The student follows the method below: Step 1 Crush three tablets, transfer the powder into a beaker and dissolve in distilled water. Step 2 Transfer the solution into a 250.0 cm3 volumetric flask and make up to the mark with distilled water. Step 3 Pipette 25.0 cm3 of the solution from Step 2 into a conical flask and add a few drops of indicator. Step 4 Titrate this solution with 0.0800 mol dm–3 sodium hydroxide, NaOH, in the burette. The equation for the neutralisation reaction is: C4H6O5 + 2NaOH C4H4O5Na2 + 2H2O (a) The student takes burette readings to the nearest 0.05 cm3. The student’s readings are shown in the table. The rough titre has been omitted. (i) Complete the table below. Titration 1 2 3 Final reading / cm3 23.60 46.70 25.65 Initial reading / cm3 0.30 23.65 2.50 Titre / cm3 ................................ ................................ ................................ [1]
3. June 2025 · Paper 2 · Q4 · 1 marks ·
4 Which diagram shows the correct way to set up apparatus for converting ethanol to ethanoic acid? water out water in A B water in water out water out water in water in water out C D Your answer [1]
4. June 2025 · AS Paper 2 · Q5(c) · 6 marks ·
(c)* 2-Chlorobutane, CH3CH2CHCl CH3, is an organic liquid with a boiling point of 70 °C. A student prepares 2-chlorobutane from butan-2-ol, CH3CH2CHOHCH3, as shown in the equation below. CH3CH2CHOHCH3 + NaCl + H2SO4 CH3CH2CHCl CH3 + NaHSO4 + H2O The student’s method is outlined below. • Add 9.25 g CH3CH2CHOHCH3 to an excess of NaCl (aq) in a pear-shaped flask. • Add an excess of concentrated sulfuric acid. • Heat the flask under reflux for about 45 minutes. The student obtains a reaction mixture containing an organic layer (density = 0.87 g cm–3) and an aqueous layer (density = 1.00 g cm–3). After purification, the percentage yield of CH3CH2CHCl CH3 is 65.0 %. Describe how the student could obtain a pure, dry sample of CH3CH2CHCl CH3 from the reaction mixture and explain the reason for carrying out each purification step. Calculate the mass of pure CH3CH2CHCl CH3 that would be expected from this preparation. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... 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5. June 2025 · Paper 2 · Q19(b)(ii) · 4 marks ·
(ii) The reaction to form 1-bromopropane from propan-1-ol is carried out in a flask. After the reaction, the flask contains a mixture of an organic layer (density = 1.35 g cm–3) and an aqueous layer (1.04 g cm–3). Describe how to obtain pure 1-bromopropane from the mixture. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [4]
6. June 2024 · AS Paper 1 · Q25(c) · 2 marks ·
(c) Primary alcohols can be oxidised under distillation to make aldehydes. Draw a labelled diagram to show how you would set up apparatus for distillation. [2]
7. June 2024 · Paper 2 · Q23(a) · 1 marks ·
23 Oil of wintergreen is a liquid used in medicine to relieve muscle pain. Compound H is a component in oil of wintergreen and can be synthesised from compound G, as shown below. The boiling point and density of compound H are stated. O O OH O OH OH Compound G Compound H boiling point = 222 °C density = 1.174 g cm−3 A student prepares a sample of compound H by the method below. Step 1 Reflux 8.97 g of compound G for 30 minutes with an excess of methanol in the presence of a small amount of sulfuric acid as a catalyst. Step 2 Add an excess of aqueous sodium carbonate, Na2CO3(aq). Two layers are obtained. Step 3 Purify the impure compound H that forms from the resulting mixture. The student follows this method and obtains 5.32 g of pure compound H. (a) Why does the student use reflux in Step 1? .......................................................................................................................................................... ..................................................................................................................................................... [1]
8. June 2024 · Paper 2 · Q23(d) · 4 marks ·
(d) Describe how to purify the impure compound H from the two layers in Step 2. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [4]
9. June 2024 · Paper 3 · Q1(d) · 5 marks ·
(d) A student is provided with hydrated copper(II) nitrate, Cu(NO3)2•3H2O. The student needs to prepare a standard solution of Cu(NO3)2•3H2O with a concentration of 0.200 mol dm–3. The student has access to usual laboratory apparatus and equipment. Describe how the student would prepare 100.0 cm3 of this solution, giving quantities, apparatus and method. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [5]
10. June 2024 · Paper 3 · Q3(b)(ii) · 3 marks ·
(ii) The student prepares a 250.0 cm3 solution of iron(II) ethanedioate by dissolving 1.295 g of FeC2O4•xH2O, in dilute sulfuric acid. The student titrates 25.0 cm3 samples of this solution with 0.0200 mol dm−3 KMnO4 in the burette. The student carries out a trial, followed by three further titrations. The diagrams show the initial burette readings and the final burette readings for the student’s three further titrations. Titration 1 Titration 2 Titration 3 Initial reading Final reading Initial reading Final reading Initial reading Final reading 0 23 23 45 0 21 1 24 24 46 1 22 2 25 25 47 2 23 All burette readings are measured to the nearest 0.05 cm3. Complete the titration table. 1 2 3 Final reading / cm3 Initial reading / cm3 Titre / cm3 [3]
11. June 2023 · AS Paper 1 · Q22(c)(i) · 1 marks · AO1
(c) A student carries out an investigation to identify an unknown Group 1 metal M. • The student reacts 2.62 g of the Group 1 metal, M, with water. A solution of the alkali, MOH(aq), is formed. • The student makes this solution of MOH(aq) up to 250.0 cm3 with water. • The student pipettes 25.0 cm3 of this MOH(aq) solution into a conical flask. • The student titrates this 25.0 cm3 volume of MOH(aq) with 0.165 mol dm–3 H2SO4(aq). The equation is shown below. 2MOH(aq) + H2SO4(aq) M2SO4(aq) + 2H2O(l) (i) Name the type of flask that the student should use to make up the 250.0 cm3 solution of MOH(aq). ...................................... flask [1]
12. June 2023 · Paper 3 · Q5(b)(i) · 2 marks · AO3
(b) Aspirin reacts with hot NaOH(aq), under reflux. (i) Draw a labelled diagram of suitable apparatus for reflux. [2]
13. June 2022 · Paper 1 · Q19(a)(i) · 2 marks · AO1
19 This question is about acids and buffer solutions. (a) Succinic acid, HOOC(CH2)2COOH, is a weak dibasic acid that is used in tablet form in health supplements. A student plans to determine the mass of succinic acid in one tablet of a succinic acid health supplement. The student carries out a titration with potassium hydroxide. The end point occurs when both acidic protons in succinic acid have been replaced as shown in Equation 19.1. HOOC(CH2)2COOH + 2KOH KOOC(CH2)2COOK + 2H2O Equation 19.1 The student uses the following method. Stage 1 The student crushes four tablets of the health supplement and dissolves the powdered tablets in distilled water. Stage 2 The student makes up the solution from Stage 1 to 250.0 cm3 in a volumetric flask. Stage 3 The student titrates 10.0 cm3 portions of the solution obtained in Stage 2 with 0.0600 mol dm–3 potassium hydroxide, using phenolphthalein as the indicator. The student carries out a trial titration, followed by three further titrations. The results are shown below. Titration Trial 1 2 3 Final burette reading / cm3 25.25 23.75 25.35 25.75 Initial burette reading / cm3 2.50 1.30 2.65 3.20 Titre / cm3 (i) Complete the table and calculate the mean titre that the student should use for analysing the results. mean titre = .................................................. cm3 [2]
14. June 2022 · AS Paper 2 · Q1(b)(i) · 4 marks · AO1
(b) A student carries out a titration to determine the mass of citric acid in a lime. The student follows the method below: • Squeeze the juice out of two limes. • Transfer the juice into a 250.0 cm3 volumetric flask and make up to the mark with distilled water. • Pipette 25.0 cm3 of the diluted lime juice into a conical flask and add a few drops of phenolphthalein indicator. • Titrate this solution with 0.800 mol dm–3 NaOH(aq). The student carries out a trial titration, followed by three further titrations. The diagram shows the burette readings for the three further titrations. Each reading is measured to the nearest 0.05 cm3. Titration 1 Titration 2 Titration 3 Initial reading Final reading Initial reading Final reading Initial reading Final reading 0 27 0 27 0 27 1 28 1 28 1 28 2 29 2 29 2 29 (i) Record the student’s burette readings in the table below. Calculate the mean titre, to the nearest 0.05 cm3, that the student should use to analyse the results. Titration 1 Titration 2 Titration 3 Final reading / cm3 Initial reading / cm3 Titre / cm3 mean titre .................................................. cm3 [4]
15. June 2022 · AS Paper 2 · Q5(c)(ii) · 3 marks · AO3
(ii) The student mixes butan-2-ol, sodium bromide and sulfuric acid in a pear-shaped flask, and refluxes the mixture. After 1 hour, the mixture in the flask has separated into two layers: an aqueous layer and an organic layer. Describe the procedures the student would need to carry out to obtain a pure, dry sample of 2-bromobutane from this mixture. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
16. June 2022 · Paper 3 · Q3(a) · 6 marks · AO2, 3
3 Information about 1-bromobutane and butan-1-ol is shown in the table. Compound Melting point / °C Boiling point / °C Density / g cm–3 1-bromobutane –113 102 1.268 butan-1-ol –90 118 0.810 A student prepares a sample of 1-bromobutane by refluxing 9.25 g of butan-1-ol with sodium bromide and sulfuric acid. After reflux, the reaction mixture is purified. The student obtains 6.10 cm3 of pure 1-bromobutane. (a)* Draw a diagram to show how the student would have carried out the reflux and calculate the percentage yield of 1-bromobutane that the student obtains. Describe how the student could have obtained pure 1-bromobutane from the reaction mixture obtained after reflux. 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17. November 2021 · AS Paper 1 · Q7 · 1 marks · AO2
7 After delivering a solution from a pipette, a droplet remains in the tip of the pipette. How should a student ensure that the pipette delivers the volume of solution stated on the pipette? A Fill the pipette just above the graduation line to compensate for the volume of the droplet that remains in the tip. B Leave the droplet in the tip. C Shake the pipette to force out the droplet left in the tip. D Use a pipette filler to force the droplet out of the tip. Your answer [1]
18. November 2021 · AS Paper 1 · Q24(c)(ii) · 2 marks · AO3
(ii) Draw a labelled diagram to show how you would set up apparatus for reflux. [2]
19. November 2021 · AS Paper 2 · Q3(a) · 1 marks · AO2
3 Glutaric acid is used in the production of polymers. The formula of glutaric acid can be represented as HOOC(CH2)nCOOH, where n is a whole number. A student carries out a titration to find the value of n. 1. The student dissolves 2.891 g of glutaric acid in water and makes up the solution to 250.0 cm3 in a volumetric flask. 2. The student transfers 25.0 cm3 of this solution into a conical flask. 3. The student titrates the solution with 0.240 mol dm–3 NaOH(aq) in the burette. Equation: HOOC(CH2)nCOOH(aq) + 2NaOH(aq) NaOOC(CH2)nCOONa(aq) + 2H2O(l) The student uses phenolphthalein as the indicator. Phenolphthalein is colourless in acid and pink in alkali. (a) State the colour change observed at the end point of the titration. Colour from ....................................................... to ....................................................... [1]
20. November 2021 · AS Paper 2 · Q3(b)(i) · 1 marks · AO2
(b) The student carries out a trial titration followed by three further titrations, 1, 2 and 3. The results are shown in the table below. Titration Trial 1 2 3 Final reading / cm3 18.70 36.55 18.30 36.60 Initial reading / cm3 0.20 18.50 0.10 18.30 Titre / cm3 (i) Complete the table to show the titre in each titration. [1]
21. November 2021 · AS Paper 2 · Q7(b) · 6 marks · AO1, 2, 3
(b)* The student’s method for the preparation is outlined below. • Add 10.0 cm3 (7.70 g) of (CH3)3COH and 30 cm3 concentrated hydrochloric acid (an excess) to a round-bottom flask. Stopper the flask. • Shake the flask until the mixture separates into two layers. Densities: (CH3)3CCl : 0.85 g cm–3; concentrated HCl : 1.18 g cm–3 After purification, the percentage yield of (CH3)3CCl is 76%. Explain how the student could obtain a pure, dry sample of (CH3)3CCl from the mixture in the flask and calculate the mass of pure (CH3)3CCl that would be expected from this preparation. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [6]
22. November 2021 · Paper 3 · Q2(a) · 2 marks · AO3
2 Europium (Ar = 152.0) reacts with dilute aqueous acid in a redox reaction, forming a solution and hydrogen gas. A student proposed three possible ionic equations for this reaction, forming europium ions with different charges: Equation 1 2Eu(s) + 2H+(aq) 2Eu+(aq) + H2(g) Equation 2 Eu(s) + 2H+(aq) Eu2+(aq) + H2(g) Equation 3 2Eu(s) + 6H+(aq) 2Eu3+(aq) + 3H2(g) The student plans to carry out an investigation to determine which equation is correct. Hydrochloric acid is used as the source of H+(aq) ions. The student’s method is outlined below. Step 1 Using a 3 decimal place balance, weigh a suitable container for the reaction. Add about 1 g of europium to the container and reweigh. Step 2 Set up apparatus for gas collection. Add an excess of dilute hydrochloric acid to the europium. Step 3 Measure the volume of gas produced. Results Mass of container = 32.795 g Mass of container + europium = 33.783 g Volume of gas collected = 152 cm3 (a) Draw a labelled diagram of suitable apparatus for this investigation. [2]
23. November 2021 · Paper 3 · Q3(a) · 5 marks · AO1, 2
3 This question is about carboxylic acids. Compound D is a cis stereoisomer of an unsaturated organic acid with the general formula CnH2n–1COOH. A student plans to analyse acid D by carrying out a titration. (a) A student first prepares 250.0 cm3 of a standard solution of 0.150 mol dm–3 Ba(OH)2 for the titration. The student is provided with solid Ba(OH)2 and usual laboratory apparatus and equipment. Describe how the student would prepare the standard solution, giving full details of quantities, apparatus and method. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
24. November 2020 · Paper 2 · Q20(a) · 6 marks · AO2, 3
20 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 prepare 4.00 g of cyclopentene by reacting cyclopentanol (boiling point 140 °C) with an acid catalyst. Equation OH + H2O The expected percentage yield of cyclopentene is 64.0%. Method The student carries out the preparation using apparatus set up for distillation, as shown below. 1 The reaction mixture is heated gently, and a distillate containing impure cyclopentene is collected. cyclopentanol and water concentrated out phosphoric acid water in water bath distillate ice-water mixture 2 The distillate has an aqueous layer and an organic layer. The student purifies the cyclopentene from the distillate. (a)* Calculate the mass of cyclopentanol that the student should use and explain how pure cyclopentene could be obtained from the distillate. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
25. November 2020 · Paper 3 · Q1(a)(i) · 2 marks · AO1
1 This question is about organic chemistry. (a) This part is about two practical techniques used in organic preparations. (i) Complete the missing labels on the diagram and name the technique. ......................................... ...................................................... ......................................... ...................................................... Heat Name of technique: ...................................................................................................... [2]
26. November 2020 · Paper 3 · Q1(a)(ii) · 2 marks · AO2
(ii) Draw a labelled diagram to show apparatus set up for filtration under reduced pressure (vacuum filtration). [2]
27. November 2020 · Paper 3 · Q4(a)(ii) · 2 marks · AO3
(ii) In Stage 1, suggest two observations that would confirm that all of metal M has reacted. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2]
28. June 2019 · AS Paper 2 · Q2(a) · 6 marks · AO2
2 Magnesium nitrate is used in fertilisers as a source of nitrogen. (a)* A student plans to prepare 250.0 cm3 of a 0.4000 mol dm–3 solution of magnesium nitrate, starting from magnesium nitrate crystals, Mg(NO3)2•6H2O. Describe how the student would prepare the solution, giving full details of quantities, apparatus and method. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
29. June 2019 · AS Paper 2 · Q5(b)(i) · 6 marks · AO2, 3
(b) Hex-1-ene is a liquid with a boiling point of 63 °C and a density of 0.67 g cm–3. Hex-1-ene can be prepared by refluxing hexan-1-ol (boiling point 157 °C) with an acid catalyst. Hexan-1-ol is a liquid with a boiling point of 157 °C and a density of 0.82 g cm–3. The equation is shown below. + H2O OH After reflux, the resulting mixture contains unreacted hexan-1-ol, hex-1-ene and water. The mixture is then purified. The expected percentage yield of hex-1-ene from hexan-1-ol is 62.5%. (i)* A student plans to prepare 4.20 g of hex-1-ene by this method. Calculate the mass of hexan-1-ol that the student should use and explain how you could obtain pure hex-1-ene from the mixture obtained after reflux. [6] ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Additional answer space if required ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................
30. June 2019 · Paper 3 · Q2(e) · 2 marks · AO3
(e) In Step 3, describe how the student can recrystallise the impure crystals to obtain pure benzoic acid. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2]
31. June 2019 · Paper 3 · Q3(a)(ii) · 1 marks · AO3
(ii) 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 experiment. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
32. June 2018 · Paper 1 · Q20(d)(i) · 2 marks ·
(d) Compound B is an iodate(V) salt of a Group 1 metal. The iodate(V) ion has the formula IO3 –. A student carries out a titration to find the formula of compound B. Step 1: The student dissolves 1.55 g of B in water and makes up the solution to 250.0 cm3 in a volumetric flask. Step 2: The student pipettes 25.00 cm3 of the solution of B into a conical flask, followed by 10 cm3 of dilute sulfuric acid and an excess of KI(aq). The iodate(V) ions are reduced to iodine, as shown below. IO3 –(aq) + 6H+(aq) + 5I–(aq) 3I2(aq) + 3H2O(l) Step 3: The resulting mixture is titrated with 0.150 mol dm–3 Na2S2O3(aq). 2S2O3 2–(aq) + I2(aq) S4O6 2–(aq) + 2I–(aq) The student repeats step 2 and step 3 until concordant titres are obtained. Titration readings Titration Trial 1 2 3 Final burette reading / cm3 24.00 47.40 23.75 47.05 Initial burette reading / cm3 0.00 24.00 0.00 23.20 Titre / cm3 Table 20.1 (i) Complete Table 20.1 and calculate the mean titre that the student should use for analysing the results. mean titre = .................................................. cm3 [2]
33. June 2018 · AS Paper 1 · Q22(a)(iii) · 2 marks ·
(iii) How could the student obtain a sample of magnesium phosphate after reacting magnesium with phosphoric acid? ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
34. June 2018 · AS Paper 2 · Q1(c)(i) · 4 marks ·
(c) The student carries out a trial, followed by three further titrations. The diagram shows the initial and final burette readings for the three further titrations. The student measures all burette readings to the nearest 0.05 cm3. Titration 1 Titration 2 Titration 3 Initial reading Final reading Initial reading Final reading Initial reading Final reading 0 27 0 27 0 27 1 28 1 28 1 28 2 29 2 29 2 29 (i) Record the student’s readings and the titres in the table below. Calculate the mean titre, to the nearest 0.05 cm3, that the student should use for analysing the results. Titration 1 Titration 2 Titration 3 Final reading/cm3 Initial reading/cm3 Titre/cm3 mean titre = .................................................. cm3 [4]
35. June 2018 · AS Paper 2 · Q1(c)(iii) · 1 marks ·
(iii) The student realised that the solution of A had not been prepared correctly. How should the student have made up the solution? ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
36. June 2018 · AS Paper 2 · Q5(a)(i) · 6 marks ·
5 (a) 1-Bromobutane is an organic liquid with a boiling point of 102 °C. A student prepares 1-bromobutane by reacting butan-1-ol with sulfuric acid and sodium bromide. The student boils the mixture for one hour. The equation is shown below. CH3CH2CH2CH2OH + H+ + Br – CH3CH2CH2CH2Br + H2O The student obtains a reaction mixture containing an organic layer (density = 1.27 g cm–3) and an aqueous layer (density = 1.00 g cm–3). (i)* Draw a labelled diagram to show how you would safely set up apparatus for the preparation. Outline a method to obtain a pure sample of 1-bromobutane from the reaction mixture. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [6]
37. June 2018 · Paper 2 · Q19(c)(i) · 2 marks ·
(c) A student hydrolyses a haloalkane, E, using the following method. • 0.0100 mol of haloalkane E is refluxed with excess NaOH(aq) to form a reaction mixture containing an organic product F. • The reaction mixture is neutralised with dilute nitric acid. • Excess AgNO3(aq) is added to the reaction mixture. 1.88 g of a precipitate G forms. Organic product, F, has a molar mass of 74.0 g mol−1 and has a chiral carbon atom. (i) Draw a labelled diagram to show how the student would carry out the hydrolysis of haloalkane E. [2]
38. June 2017 · Paper 1 · Q19(a) · 3 marks ·
19 Aqueous solutions of hydrogen peroxide, H2O2(aq), decompose as in the equation below. 2H2O2(aq) 2H2O(l) + O2(g) A student investigates the decomposition of H2O2(aq) by measuring the volume of oxygen gas produced over time. All gas volumes are measured at room temperature and pressure. The student uses 25.0 cm3 of 2.30 mol dm–3 H2O2. From the results, the student determines the concentration of H2O2(aq) at each time. The student then plots a concentration–time graph. 2.5 2.0 1.5 [H2O2(aq)] / mol dm–3 1.0 0.5 0.0 0 500 1000 1500 2000 2500 3000 time / s (a) Determine the total volume of oxygen, measured at room temperature and pressure, that the student should be prepared to collect in this investigation. Suggest apparatus that would allow this gas volume to be collected, indicating clearly the scale of working. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
39. June 2017 · Paper 3 · Q4(a)(i) · 4 marks ·
4 This question is about weak acids. (a) Compound A is a weak monobasic acid. A student is supplied with a 250.0 cm3 solution prepared from 2.495 g of A. The student titrates 25.0 cm3 samples of this solution with 0.0840 mol dm−3 NaOH in the burette. The student carries out a trial, followed by the three further titrations. The diagrams show the initial burette readings and the final burette readings for the student’s three further titrations. All burette readings are measured to the nearest 0.05 cm3. Titration 1 Titration 2 Titration 3 Initial reading Final reading Initial reading Final reading Initial reading Final reading 0 23 23 45 9 32 1 24 24 46 10 33 2 25 25 47 11 34 (i) Record the student’s readings and the titres in an appropriate format. Calculate the mean titre that the student should use for analysing the results. mean titre = .................................................. cm3 [4]
40. June 2016 · AS Paper 2 · Q1(c)(i) · 2 marks · AO3
3 (c) A student reacts a Group 2 metal, M, with water. M(s) + 2H2O(l) M(OH)2(aq) + H2(g) The student measures the volume of hydrogen gas produced. 0.162 g of the metal produces 97.0 cm3 of gas measured at room temperature and pressure. (i) Draw a labelled diagram of the apparatus that can be used to carry out this experiment. [2]
41. June 2016 · AS Paper 2 · Q5(c) · 3 marks · AO3
(c) Outline a method that could be used to obtain the results that are plotted on the graph. Your answer should include the apparatus required and the procedure for the experiment. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
42. June 2016 · AS Paper 2 · Q6(c)(ii) · 2 marks · AO3
15 (ii) A student plans to carry out this oxidation using the apparatus shown in the diagram. Give one reason why the apparatus is not suitable and describe a more suitable way of carrying out this oxidation. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]

Mark schemes

1. June 2025 · Paper 1 · Q20(a)(i)
Mark scheme June 2025 Paper 1 Q20(a)(i)
2. June 2025 · AS Paper 2 · Q3(a)(i)
Mark scheme June 2025 Paper 2 Q3(a)(i)
3. June 2025 · Paper 2 · Q4
Mark scheme June 2025 Paper 2 Q4
4. June 2025 · AS Paper 2 · Q5(c)
Mark scheme June 2025 Paper 2 Q5(c)
5. June 2025 · Paper 2 · Q19(b)(ii)
Mark scheme June 2025 Paper 2 Q19(b)(ii)
6. June 2024 · AS Paper 1 · Q25(c)
Mark scheme June 2024 Paper 1 Q25(c)
7. June 2024 · Paper 2 · Q23(a)
Mark scheme June 2024 Paper 2 Q23(a)
8. June 2024 · Paper 2 · Q23(d)
Mark scheme June 2024 Paper 2 Q23(d)
9. June 2024 · Paper 3 · Q1(d)
Mark scheme June 2024 Paper 3 Q1(d)
10. June 2024 · Paper 3 · Q3(b)(ii)
Mark scheme June 2024 Paper 3 Q3(b)(ii)
11. June 2023 · AS Paper 1 · Q22(c)(i)
Mark scheme June 2023 Paper 1 Q22(c)(i)
12. June 2023 · Paper 3 · Q5(b)(i)
Mark scheme June 2023 Paper 3 Q5(b)(i)
13. June 2022 · Paper 1 · Q19(a)(i)
Mark scheme June 2022 Paper 1 Q19(a)(i)
14. June 2022 · AS Paper 2 · Q1(b)(i)
Mark scheme June 2022 Paper 2 Q1(b)(i)
15. June 2022 · AS Paper 2 · Q5(c)(ii)
Mark scheme June 2022 Paper 2 Q5(c)(ii)
16. June 2022 · Paper 3 · Q3(a)
Mark scheme June 2022 Paper 3 Q3(a)
17. November 2021 · AS Paper 1 · Q7
Mark scheme November 2021 Paper 1 Q7
18. November 2021 · AS Paper 1 · Q24(c)(ii)
Mark scheme November 2021 Paper 1 Q24(c)(ii)
19. November 2021 · AS Paper 2 · Q3(a)
Mark scheme November 2021 Paper 2 Q3(a)
20. November 2021 · AS Paper 2 · Q3(b)(i)
Mark scheme November 2021 Paper 2 Q3(b)(i)
21. November 2021 · AS Paper 2 · Q7(b)
Mark scheme November 2021 Paper 2 Q7(b)
22. November 2021 · Paper 3 · Q2(a)
Mark scheme November 2021 Paper 3 Q2(a)
23. November 2021 · Paper 3 · Q3(a)
Mark scheme November 2021 Paper 3 Q3(a)
24. November 2020 · Paper 2 · Q20(a)
Mark scheme November 2020 Paper 2 Q20(a)
25. November 2020 · Paper 3 · Q1(a)(i)
Mark scheme November 2020 Paper 3 Q1(a)(i)
26. November 2020 · Paper 3 · Q1(a)(ii)
Mark scheme November 2020 Paper 3 Q1(a)(ii)
27. November 2020 · Paper 3 · Q4(a)(ii)
Mark scheme November 2020 Paper 3 Q4(a)(ii)
28. June 2019 · AS Paper 2 · Q2(a)
Mark scheme June 2019 Paper 2 Q2(a)
29. June 2019 · AS Paper 2 · Q5(b)(i)
Mark scheme June 2019 Paper 2 Q5(b)(i)
30. June 2019 · Paper 3 · Q2(e)
Mark scheme June 2019 Paper 3 Q2(e)
31. June 2019 · Paper 3 · Q3(a)(ii)
Mark scheme June 2019 Paper 3 Q3(a)(ii)
32. June 2018 · Paper 1 · Q20(d)(i)
Mark scheme June 2018 Paper 1 Q20(d)(i)
33. June 2018 · AS Paper 1 · Q22(a)(iii)
Mark scheme June 2018 Paper 1 Q22(a)(iii)
34. June 2018 · AS Paper 2 · Q1(c)(i)
Mark scheme June 2018 Paper 2 Q1(c)(i)
35. June 2018 · AS Paper 2 · Q1(c)(iii)
Mark scheme June 2018 Paper 2 Q1(c)(iii)
36. June 2018 · AS Paper 2 · Q5(a)(i)
Mark scheme June 2018 Paper 2 Q5(a)(i)
37. June 2018 · Paper 2 · Q19(c)(i)
Mark scheme June 2018 Paper 2 Q19(c)(i)
38. June 2017 · Paper 1 · Q19(a)
Mark scheme June 2017 Paper 1 Q19(a)
39. June 2017 · Paper 3 · Q4(a)(i)
Mark scheme June 2017 Paper 3 Q4(a)(i)
40. June 2016 · AS Paper 2 · Q1(c)(i)
Mark scheme June 2016 Paper 2 Q1(c)(i)
41. June 2016 · AS Paper 2 · Q5(c)
Mark scheme June 2016 Paper 2 Q5(c)
42. June 2016 · AS Paper 2 · Q6(c)(ii)
Mark scheme June 2016 Paper 2 Q6(c)(ii)