Practical skills: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on Practical skills, 2019–2025, with its mark scheme and examiner’s report.

All 286 questions on Practical skills, as a list

June 2025, AS Unit 3, Q2(a)(iv) (2 marks): In school laboratories, wooden splints are sometimes used in the flame test instead of the unreactive metal wires. Give one advantage and one disadvantage of us
June 2025, AS Unit 3, Q3(b)(i) (1 mark): The filter paper was soaked in tap water prior to the experiment and then gently shaken to remove excess water before use. Suggest the reason that deionised or
June 2025, AS Unit 3, Q3(b)(ii) (1 mark): Identify, by name or formula, one ion which might be present in tap water that might cause the formation of a white precipitate on the left-hand side of the fil
June 2025, AS Unit 3, Q3(b)(iii) (1 mark): Give the reason that the formation of any precipitate in part (b)(ii) will not interfere significantly with the formation of the red precipitate. (1)
June 2025, AS Unit 3, Q4(b) (2 marks): State the purpose of both the anhydrous calcium chloride and the ceramic wool in the combustion tube. (2)
June 2025, AS Unit 3, Q4(c) (1 mark): Give the reason why the iron wool must not be heated until about half a minute after the reaction to produce chlorine has begun. (1)
June 2025, AS Unit 3, Q4(d) (1 mark): State the purpose of the sodium hydroxide. (1)
June 2025, AS Unit 3, Q5(d) (4 marks): Justify how the equipment and the procedure could be improved to give a more accurate value for the enthalpy change of the reaction. (4)
June 2025, Unit 6, Q1(a)(i) (2 marks): Heat a small amount A is a (2) of solid A in a test hydrated salt. 1 tube, holding some cobalt chloride paper at the mouth of the test tube. 2
June 2025, Unit 6, Q2(c)(i) (2 marks): Complete the table and calculate the mean titre in cm3. (2)
June 2025, Unit 6, Q3(b) (2 marks): Explain why a burette, and not a measuring cylinder, is used to add the starch solution in Step 3, even though the concentration of starch indicator does not ne
June 2025, Unit 6, Q4(a) (1 mark): State the main safety precaution, other than wearing safety spectacles and a laboratory coat, that should be taken when weighing the phenol in Step 1. (1)
June 2025, Unit 6, Q4(b) (1 mark): Give one reason why Step 2 must be performed in a fume cupboard. (1)
June 2025, Unit 6, Q4(d) (2 marks): Give two reasons why the crude product is washed with water in Step 3. (2)
June 2025, Unit 6, Q4(e)(i) (1 mark): The recrystallisation in Step 4 was carried out using this method: • transfer the crude product to a boiling tube and cover in ethanol • place the boiling tube
June 2025, Unit 6, Q4(e)(ii) (2 marks): Explain why the crystals are washed with cold ethanol. (2)
June 2025, Unit 6, Q4(f) (3 marks): Draw a labelled diagram of the apparatus that could be used to measure the melting temperature of phenyl benzoate in Step 5. You should assume that electrical e
January 2025, AS Unit 3, Q2(c) (2 marks): The diagram shows the burette readings from Steps 4 and 5. Burette reading from Step 4 Burette reading from Step 5 Record the burette readings, and hence the vo
January 2025, AS Unit 3, Q2(f)(i) (1 mark): Calculate the percentage uncertainty in the mass of magnesium used in the experiment. (1)
January 2025, AS Unit 3, Q2(f)(ii) (1 mark): The student wanted to reduce the percentage uncertainty by using double the mass of magnesium. Give the reason why the experiment outlined in the procedure coul
January 2025, AS Unit 3, Q3(c)(i) (1 mark): Name the piece of apparatus that should be used to add the ethanedioic acid solution, H2C2O4(aq), to the conical flask. (1)
January 2025, AS Unit 3, Q4(a) (1 mark): Give one reason, relating to safety, why the hydrochloric acid is added to the separating funnel 3 cm3 at a time, and not all at once, in Step 2. (1)
January 2025, AS Unit 3, Q4(b) (2 marks): Draw a labelled diagram of the separating funnel at the end of Step 3. [Density of 2‑chloro‑2‑methylpropane = 0.85 g cm–3] (2)
January 2025, AS Unit 3, Q4(c) (1 mark): Sodium hydrogencarbonate solution is added to remove acid impurities in Step 4. Give the reason why a stronger alkali, such as sodium hydroxide solution, should
January 2025, AS Unit 3, Q4(d) (1 mark): State the role of the sodium sulfate in Step 5. (1)
January 2025, AS Unit 3, Q4(e) (4 marks): Identify two changes that must be made to the apparatus shown before distilling in Step 6, giving a reason for each change. (4) water from tap still head pear-s
January 2025, Unit 6, Q1(b)(ii) (3 marks): Draw a labelled diagram of the apparatus used to filter under reduced pressure. (3)
January 2025, Unit 6, Q1(b)(iii) (2 marks): Give two advantages of filtering under reduced pressure compared to gravity filtration. (2)
January 2025, Unit 6, Q2(b) (2 marks): The student suggested using the apparatus shown to carry out the heating under reflux in Step 2. There are two mistakes with this set-up. water in water out hea
January 2025, Unit 6, Q2(c)(iv) (3 marks): Explain why a student carrying out Step 4 was told to ensure they used the minimum amount of hot ethanol to dissolve the azo dye. (3)
January 2025, Unit 6, Q2(c)(v) (1 mark): State how the purified azo dye could be dried in Step 5. (1)
January 2025, Unit 6, Q2(d) (3 marks): The hazard symbols present on the reagent bottle containing phenylamine are shown. State three precautions, other than wearing safety glasses and a laboratory c
October 2024, AS Unit 3, Q2(a)(i) (3 marks): Draw two lines of best-fit to determine the maximum temperature change at the point of neutralisation. (3) Volume of hydrochloric acid at neutralisation cm3 Max
October 2024, AS Unit 3, Q2(c)(i) (1 mark): Give an improvement to the experimental method that will increase the accuracy of the calculated titre value. (1)
October 2024, AS Unit 3, Q2(c)(ii) (1 mark): Give an improvement to the experimental method that will increase the accuracy of the calculated enthalpy change of neutralisation. (1)
October 2024, AS Unit 3, Q3(a) (3 marks): Draw a labelled diagram of the distillation apparatus including a thermometer. (3)
October 2024, AS Unit 3, Q4(a) (2 marks): Label the axes of the graph. (2)
October 2024, AS Unit 3, Q4(b)(ii) (3 marks): Calculate the maximum rate of foam production measured for PbO2. Include units with your answer. (3) Units
October 2024, AS Unit 3, Q4(b)(iii) (1 mark): Suggest why the value calculated from the graph may not be accurate. (1)
October 2024, AS Unit 3, Q4(c)(i) (1 mark): In most kinetics experiments the rate of reaction decreases with time. Suggest a reason why the rate of reaction seems to increase in this experiment. (1)
October 2024, AS Unit 3, Q4(c)(ii) (2 marks): In a repeat experiment, a larger measuring cylinder was used so that it contained all the foam produced. Sketch the expected graph of the volume reached by the
October 2024, AS Unit 3, Q4(d)(i) (1 mark): Draw the hazard symbol that should be displayed on the bottle of hydrogen peroxide. (1)
October 2024, AS Unit 3, Q4(d)(ii) (1 mark): State one safety precaution that should be taken when using the hydrogen peroxide, other than wearing a lab coat and safety spectacles. (1)
October 2024, AS Unit 3, Q4(d)(iii) (1 mark): The risk of harm to students needs to be reduced before they carry out this experiment in class. Suggest another control measure to reduce the risk for students
October 2024, AS Unit 3, Q4(d)(iv) (1 mark): Give a reason why, during the experiment, the measuring cylinders should be placed in a tray. (1)
October 2024, Unit 5, Q18(c)(i) (3 marks): Plot a graph of absorbance against concentration using the data in the table. (3)
October 2024, Unit 5, Q18(c)(iii) (1 mark): Give one possible reason why any concentrations of copper(II) sulfate determined from the graph of values over 0.50 mol dm−3 are uncertain. (1)
October 2024, Unit 6, Q3(a)(i) (3 marks): Describe how to make 250.0 cm3 of a solution of ethanedioic acid in Step 1. (3)
October 2024, Unit 6, Q3(a)(ii) (2 marks): Explain why, in Step 2, the ethanedioic acid solution was measured using a 25.0 cm3 volumetric pipette but the dilute sulfuric acid was measured using a 25 cm3
October 2024, Unit 6, Q4(a) (2 marks): Phenylamine, used in Reaction 1, is labelled with the following hazard symbols. State the meaning of each symbol. (2)
October 2024, Unit 6, Q4(b)(ii) (2 marks): Draw a labelled diagram of the apparatus used to filter off the crystals under reduced pressure in Step 5. (2)
October 2024, Unit 6, Q4(b)(iii) (3 marks): Outline how the melting temperature of the crystals may be measured to ensure that an accurate value is obtained. (3)
June 2024, AS Unit 3, Q1(c)(i) (2 marks): Give two reasons why the second set of apparatus gives a more accurate measurement of the volume of gas given off. Justify your answers. (2)
June 2024, AS Unit 3, Q2(i) (1 mark): A small quantity of water is removed by the drying agent anhydrous calcium chloride. Complete the equation by adding the formula of the product including its st
June 2024, AS Unit 3, Q2(b) (1 mark): The potassium bromide used in Step 3 was initially lumpy and not a fine powder. State the apparatus that would be suitable for breaking up the lumps of potassiu
June 2024, AS Unit 3, Q2(d) (3 marks): Complete the labelled diagram of the distillation apparatus used in Step 4. (3) round-bottomed ﬂask reaction mixture of ethanol, sulfuric acid A and potassium b
June 2024, AS Unit 3, Q2(e) (1 mark): Identify the solid particles labelled A in the flask that have been added to promote smooth boiling. (1)
June 2024, AS Unit 3, Q2(f) (1 mark): Bromoethane is very volatile. Suggest what could be done with the small beaker, used in Step 5 to collect bromoethane, in order to prevent the loss of the bromo
June 2024, AS Unit 3, Q2(g) (2 marks): Describe how to use a separating funnel to remove the aqueous layer from the bromoethane collected in Step 6. [Densities: bromoethane = 1.47 g cm–3 water = 1.00
June 2024, AS Unit 3, Q2(h) (1 mark): State why the bromoethane would not be dried in Step 7 by placing in a warm oven. (1)
June 2024, AS Unit 3, Q3(a)(ii) (2 marks): The 3‑way tap can be used to prevent more chlorine gas from entering the equilibrium system. Identify Q and state why it is necessary. (2)
June 2024, AS Unit 3, Q4(a) (1 mark): Give the reason why the polystyrene cup in Step 1 was placed in a beaker. (1)
June 2024, AS Unit 3, Q4(b) (1 mark): State the purpose of measuring the temperature every 30 seconds for 2½ minutes in Step 2. (1)
June 2024, AS Unit 3, Q4(c) (2 marks): Explain why the temperature was not measured at 3 minutes. (2)
June 2024, AS Unit 3, Q4(d)(i) (2 marks): Determine the maximum temperature change, ∆T , for this reaction, using the graph. You must show your working on the graph. (2)
June 2024, AS Unit 3, Q4(d)(iii) (1 mark): Give a possible reason why the temperature does not appear to change at various times, such as 5½ to 6½ minutes. (1)
June 2024, Unit 6, Q4(c) (3 marks): Draw a diagram of the apparatus used in Step 3 when the mixture is heated under reflux. (3)
June 2024, Unit 6, Q4(d) (2 marks): Describe how to wash the organic layer with sodium carbonate solution in Step 5. (2)
June 2024, Unit 6, Q5(a)(i) (2 marks): Describe how to carry out Step 4. You should identify both how to perform the test and how you would know all the ammonia had been evolved. (2)
June 2024, Unit 6, Q5(a)(ii) (1 mark): Containers of ammonia gas have the following hazard warning signs. State these two hazards associated with ammonia. (1)
June 2024, Unit 6, Q5(a)(iii) (1 mark): Give a precaution to reduce the risk when carrying out Steps 3 and 4. It is assumed that safety goggles and a laboratory coat are used. (1)
June 2024, Unit 6, Q5(c) (4 marks): Another student carried out the experiment but did not titrate all the contents of the conical flask in Step 6. Instead they transferred the contents of the con
June 2024 (R), AS Unit 3, Q1(a) (1 mark): Complete the diagram to show the apparatus that could be used to measure the volume of gas. (1) 0.150 mol dm–3 sulfuric acid and 0.200 g sodium sulﬁte
June 2024 (R), AS Unit 3, Q1(e) (1 mark): State why the experiment should be carried out in a fume cupboard. (1)
June 2024 (R), AS Unit 3, Q2(a)(ii) (2 marks): State two precautions, other than wearing safety goggles, that should be taken during the experiment. (2)
June 2024 (R), AS Unit 3, Q4(d) (1 mark): State why it is not necessary to repeat these experiments for each halogenoalkane. (1)
June 2024 (R), AS Unit 3, Q5(a) (2 marks): Complete the list to show the correct order of the steps. (2) A
June 2024 (R), AS Unit 3, Q5(b)(ii) (1 mark): State the purpose of adding anhydrous sodium sulfate in Step D. (1)
January 2024, AS Unit 1, Q20(e)(iv) (1 mark): State how the magnesium sulfate solution could be separated from the mixture produced in this experiment. (1)
January 2024, AS Unit 3, Q2(e)(i) (1 mark): Student B added too much deionised water in Step 2. State how Student B should correct this mistake. (1)
January 2024, AS Unit 3, Q3(d) (4 marks): Describe how to carry out Step 5, using a separating funnel. [Density of cyclohexane = 0.78 g cm–3] (4)
January 2024, AS Unit 3, Q3(e)(i) (1 mark): State what is meant by Symbol 3. (1)
January 2024, AS Unit 3, Q3(e)(ii) (2 marks): Give two safety precautions that should be taken to reduce the risk in Step 5. Assume eye protection, gloves and a laboratory coat are being worn. (2)
January 2024, AS Unit 3, Q4(a)(i) (1 mark): Calculate the density of an ethanol‑water mixture, sample A, 5.00 cm3 of which has a mass of 4.75 g. (1)
January 2024, AS Unit 3, Q4(a)(ii) (3 marks): Plot a graph of density against the percentage of ethanol by volume. (3) Density / g cm–3 percentage ethanol by volume
January 2024, AS Unit 3, Q4(a)(iii) (1 mark): Determine the percentage of ethanol by volume in sample A using your answer to (a)(i) and the graph in (a)(ii). Show your working on the graph. (1)
January 2024, AS Unit 3, Q4(b)(i) (2 marks): Explain why the reaction mixture is heated as shown, instead of heating under reflux. (2)
January 2024, AS Unit 3, Q4(b)(ii) (2 marks): Explain why the water is passed through the condenser in the direction shown. (2)
January 2024, AS Unit 3, Q4(d) (3 marks): Whilst evaluating the method used in (c), the student found a diagram of an alternative apparatus as shown. pump stirrer thermometer copper coil water spirit bu
January 2024, Unit 5, Q12(a) (1 mark): 5.00 g of sodium thiosulfate was dissolved in deionised water and the solution made up to 250.0 cm3 in a volumetric flask. The volumetric flask has an uncertain
January 2024, Unit 6, Q1(d) (1 mark): The student researched further tests for the anion present in D. A test was found which involved the addition of sodium hydroxide solution followed by aluminium
January 2024, Unit 6, Q3(a)(i) (1 mark): Suggest why only an approximate volume of sulfuric acid was used. (1)
January 2024, Unit 6, Q3(b)(i) (1 mark): Suggest why sulfur dioxide is advised to be prepared in this way. (1)
January 2024, Unit 6, Q3(c)(i) (1 mark): State a suitable method to remove the unreacted tin. (1)
January 2024, Unit 6, Q4(a) (2 marks): The use of phenylammonium chloride is preferred to the use of phenylamine in this preparation. Compound State at room temperature Hazard symbols phenylamine liq
January 2024, Unit 6, Q4(c)(i) (2 marks): The filter paper used should fit in the funnel and lie flat on the base of the Büchner funnel rather than curl up the sides of the funnel. correct incorrect Exp
January 2024, Unit 6, Q4(c)(ii) (2 marks): Explain why the solid collected in Step 4 is washed with a small volume of cold water. (2)
January 2024, Unit 6, Q4(d) (1 mark): In Step 5 the recrystallisation of phenylethanamide involves hot filtration. State the purpose of this filtration. (1)
January 2024, Unit 6, Q4(e) (1 mark): Give the two effects of impurities on the melting temperature range of phenylethanamide. (1)
October 2023, AS Unit 3, Q2(a) (3 marks): Draw a diagram of the apparatus used to carry out the reaction and collect the carbon dioxide produced over water in a 100 cm3 measuring cylinder. Do not show s
October 2023, AS Unit 3, Q2(c) (1 mark): A student suggested that the mass of calcium carbonate could be measured by weighing the weighing bottle empty and then when containing the solid. Give a reason
October 2023, AS Unit 3, Q2(d)(i) (3 marks): Plot the data on the grid. (3) 0 0
October 2023, AS Unit 3, Q2(d)(ii) (2 marks): Use the graph to determine the volume of carbon dioxide formed when 0.25 g of calcium carbonate is used. You must show your working on the graph. (2)
October 2023, AS Unit 3, Q3(a)(i) (1 mark): Complete the table by identifying the hazards. (1)
October 2023, AS Unit 3, Q3(a)(ii) (2 marks): For each compound, state one way in which the risk due to the hazard shown could be reduced when carrying out this preparation. (2) Cyclohexanol Cyclohexene
October 2023, AS Unit 3, Q3(b) (1 mark): State how anti-bumping granules make liquids boil more smoothly. (1)
October 2023, AS Unit 3, Q3(c) (2 marks): The diagram shows the apparatus used for fractional distillation in Step 4. heat Suggest two reasons why fractional distillation is used rather than simple dist
October 2023, AS Unit 3, Q3(d) (2 marks): Draw a diagram of the separating funnel and its contents in Step 5, labelling each layer. (2)
October 2023, AS Unit 3, Q3(e) (2 marks): Explain the change in appearance of the liquid when it is allowed to stand with anhydrous calcium chloride in Step 6. (2)
October 2023, AS Unit 3, Q3(f) (1 mark): State a suitable temperature range for collecting the distillate in Step 7. (1)
October 2023, AS Unit 3, Q4(b) (1 mark): The diagram shows the burette at the end-point of the rough titration. 23 24 25 Give the burette reading for this rough titration. (1)
October 2023, AS Unit 3, Q4(c) (3 marks): The student refilled the burette and prepared a second conical flask by adding sodium carbonate solution and methyl orange indicator. Describe how an accurate t
June 2023, AS Unit 3, Q3(a)(i) (2 marks): Explain why apparatus E is not suitable for the oxidation of butan‑1‑ol to butanoic acid. (2)
June 2023, AS Unit 3, Q3(a)(ii) (1 mark): Give a different reason why apparatus G is also not suitable for the oxidation of butan‑1‑ol to butanoic acid. (1)
June 2023, AS Unit 3, Q3(a)(iii) (2 marks): Explain why, in apparatus F, the water should flow in from the bottom of the condenser. (2)
June 2023, AS Unit 3, Q4(b)(i) (1 mark): Calculate the percentage error in this student’s value. The data book value for the molar volume of hydrogen under these conditions is 23.9 dm3 mol–1. (1)
June 2023, Unit 6, Q1(c)(ii) (2 marks): Describe a test, and its positive result, that the student could have carried out to show the presence of sulfate ions. (2)
June 2023, Unit 6, Q2(a)(ii) (1 mark): State the precaution that you would take to minimise the risk of carrying out this test on the misty fumes. Assume gloves, safety goggles and laboratory coat ar
June 2023, Unit 6, Q4(a) (1 mark): An ice bath is a mixture of ice and water in a beaker. Suggest an advantage of using an ice bath in Steps 1 and 3 rather than a beaker containing only ice cubes
June 2023, Unit 6, Q4(c) (3 marks): One student drew the suction filtration apparatus in Step 6 as shown. base of Buchner funnel flask Identify the three ways in which this diagram is incorrect. Y
June 2023, Unit 6, Q4(d) (4 marks): Describe the stages in the recrystallisation of methyl 3‑nitrobenzoate in Step 7, stating which stages are required to remove the insoluble and soluble impuriti
June 2023, Unit 6, Q4(e)(i) (1 mark): The crystals must be dried before the melting temperature can be determined. Methyl 3‑nitrobenzoate cannot be dried by the addition of a solid drying agent such
June 2023, Unit 6, Q4(e)(ii) (1 mark): State how the crystals of methyl 3‑nitrobenzoate could be dried. (1)
June 2023, Unit 6, Q4(g) (2 marks): The melting temperature range of methyl 3‑nitrobenzoate is given in a data book as 78–80 °C. Suggest a melting temperature range for a sample of the methyl 3‑ni
January 2023, AS Unit 3, Q2(a)(ii) (1 mark): Draw the hazard symbol which should be on a bottle of ethanol. (1)
January 2023, AS Unit 3, Q2(b)(iv) (1 mark): The uncertainty in each reading of the thermometer was ±0.1°C. Calculate the percentage uncertainty in the temperature change in the student’s experiment. (1)
January 2023, AS Unit 3, Q2(c)(i) (1 mark): State how the changes in the experiment improve the percentage uncertainties in the measurement of mass and temperature. No calculation is required. (1)
January 2023, AS Unit 3, Q2(c)(ii) (2 marks): Explain how the difference between uncertainty and accuracy led the teacher to make this statement. (2)
January 2023, AS Unit 3, Q3(a)(ii) (1 mark): Give a reason why the student inverted the volumetric flask several times in Step 1. (1)
January 2023, AS Unit 3, Q3(a)(iii) (2 marks): The sodium hydroxide solution was labelled with the hazard label. The student wore safety glasses and placed the burette below head height while filling it with
January 2023, Unit 6, Q1(c)(iii) (1 mark): Pure ethanoic acid is corrosive. Identify the appropriate control measure to reduce the risk associated with this hazard. Assume the student carried out the add
January 2023, Unit 6, Q1(c)(iv) (2 marks): Describe the corrosive hazard label present on a bottle containing pure ethanoic acid. You may use a diagram in your answer. (2)
January 2023, Unit 6, Q4(a) (2 marks): Give two reasons why it is often necessary to heat a reaction under reflux as in Step 3. (2)
January 2023, Unit 6, Q4(c) (3 marks): Draw a labelled diagram of the apparatus used for filtration under reduced pressure in Step 7. (3)
January 2023, Unit 6, Q4(d)(i) (2 marks): Draw a labelled diagram of the apparatus you would use to measure the melting temperature. (2)
January 2023, Unit 6, Q4(d)(ii) (2 marks): State how this melting temperature determination would show that a pure sample of 2‑ethanoylaminobenzoic acid had been prepared. (2)
October 2022, AS Unit 3, Q3(a)(i) (2 marks): Plot the data on the grid. (2)
October 2022, AS Unit 3, Q3(c) (1 mark): Suggest why some of the precipitate heights may be above the maximum height expected. Assume there were no measurement errors. (1)
October 2022, AS Unit 3, Q3(d) (1 mark): The metal nitrate is toxic. Draw the hazard symbol that should be displayed on the bottle. (1)
October 2022, AS Unit 3, Q4(b) (4 marks): Draw a labelled diagram of the apparatus that is required to prepare and collect a sample of propanal by heating propan‑1‑ol with acidified potassium dichromate
October 2022, AS Unit 3, Q4(c)(i) (1 mark): State why an electric heater should be used rather than a Bunsen burner to heat these reaction mixtures. (1)
October 2022, Unit 6, Q1(a)(ii) (1 mark): Add acidified A white precipitate forms X is barium chloride solution
October 2022, Unit 6, Q1(b) (4 marks): Another cobalt salt, CoCl2.xH2O(s), decomposes when heated. CoCl2.xH2O(s) → CoCl2(s) + xH2O(g) Devise an outline procedure to determine the mass of water produc
October 2022, Unit 6, Q2(a) (2 marks): Describe how all the solution containing excess sodium hydroxide is separated from the sand in Step 3. (2)
October 2022, Unit 6, Q2(b) (2 marks): Describe how to make the 250.0 cm3 of sodium hydroxide solution in Step 4. (2)
October 2022, Unit 6, Q2(d)(i) (3 marks): Explain the effect, if any, on the titre value and hence on the calculated percentage of ammonium sulfate in the fertiliser. (3)
October 2022, Unit 6, Q2(d)(ii) (1 mark): State how the student could have confirmed that all the ammonia was boiled off in Step 2. (1)
October 2022, Unit 6, Q3(b) (2 marks): Explain why it is important from time to time in Step 4 either to invert the separating funnel and open the tap, or to remove its stopper. Include an equation t
October 2022, Unit 6, Q3(c) (2 marks): A student set up a separating funnel in Step 5 as shown and opened the tap to remove the lower layer. Explain what happens. Assume that the funnel is supported
October 2022, Unit 6, Q3(d)(i) (1 mark): Identify, by name or formula, a suitable drying agent for use in Step 5. (1)
October 2022, Unit 6, Q3(d)(ii) (1 mark): State how a student would decide whether or not more drying agent was needed in Step 5. (1)
October 2022, Unit 6, Q3(d)(iii) (1 mark): Name the technique used to obtain a pure sample of the dry organic liquid in Step 6. (1)
October 2022, Unit 6, Q4(a) (1 mark): Name the apparatus which is most suitable to remove the samples from the reaction mixture. (1)
June 2022, AS Unit 3, Q1(a)(i) (1 mark): Plot a graph of temperature against time on the grid. (1) 70.0 60.0 50.0 40.0 Temperature / °C 30.0 20.0 10.0 0.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 T
June 2022, AS Unit 3, Q1(a)(ii) (3 marks): Use the graph to determine the maximum temperature change, ΔT, in this experiment. You must show your working on the graph. (3) ΔT = °C
June 2022, AS Unit 3, Q1(a)(iii) (1 mark): State why using a series of measurements gives a more accurate temperature change than taking the initial and highest temperatures. (1)
June 2022, AS Unit 3, Q1(c) (2 marks): Identify two improvements in the experimental procedure that would improve the accuracy of the result, other than repeating the experiment. Justify your answers
June 2022, AS Unit 3, Q2(b)(i) (1 mark): Calculate the experimental error for the second student. [Ar of potassium = 39.1] (1)
June 2022, AS Unit 3, Q2(b)(ii) (3 marks): The second student calculated the Ar value of M to be 37.52 with a total percentage uncertainty of 4.5 %. Comment on the value of 37.52 obtained by this student
June 2022, AS Unit 3, Q2(b)(iii) (2 marks): The first student suggested that the burette was the biggest source of experimental uncertainty. Explain how the percentage uncertainty of the burette reading c
June 2022, AS Unit 3, Q2(b)(iv) (4 marks): The second student was told that using a beaker to prepare their standard solution was incorrect. Describe the steps the student should take to make a standard
June 2022, AS Unit 3, Q3(a) (1 mark): Give the most suitable piece of apparatus for measuring the cyclohexanol in Step 1. (1)
June 2022, AS Unit 3, Q3(b) (2 marks): Explain why adding phosphoric(V) acid slowly, with cooling and swirling, in Step 2 results in a higher yield of cyclohexene. (2)
June 2022, AS Unit 3, Q3(c) (1 mark): In Step 3 anti‑bumping granules are present to promote smooth boiling in the mixture. Give a reason, other than damage to equipment, why bumping should be avoid
June 2022, AS Unit 3, Q3(d) (2 marks): Explain why, in Step 4, the distillate is collected in a temperature range of 80 °C to 90 °C. (2) Substance Boiling temperature / °C Cyclohexanol 162 Cyclohexen
June 2022, AS Unit 3, Q3(e)(ii) (2 marks): After the washing in Step 5, the separating funnel contains two layers. Draw a diagram of the separating funnel, labelling its contents. (2) Substance Density /
June 2022, AS Unit 3, Q3(e)(iii) (1 mark): Suggest what might be removed by washing the product with deionised water in Step 6. (1)
June 2022, AS Unit 3, Q3(f) (2 marks): Identify from the list shown one substance that could be used as a drying agent in Step 7 of this procedure. Justify your choice. (2) C2H5OH(l) Ca(OH)2(s) CuSO4
June 2022, Unit 5, Q6 (1 mark): A titre has an uncertainty of 0.32 %. The uncertainty of each burette reading is ±0.05 cm3 . What is the most likely value of the titre in cm3 ? A 6.40 B 15.60
June 2022, Unit 6, Q1(b)(i) (1 mark): Identify, by name or formula, the gas given off when B is warmed with aqueous sodium hydroxide. (1)
June 2022, Unit 6, Q1(b)(ii) (2 marks): Give the formulae of the ions of the salt in B. (2)
June 2022, Unit 6, Q2(b)(i) (4 marks): The orange precipitates produced on the addition of Brady’s reagent to samples of C and E are called derivatives. The melting temperatures of derivatives are us
June 2022, Unit 6, Q3(a)(i) (2 marks): State two hazards in this experiment, giving the precautions you would take to minimise the risk associated with each hazard. Assume safety spectacles and a lab
June 2022, Unit 6, Q3(a)(iii) (1 mark): Excess nitric acid must be neutralised before the iodide ions are added in Stage 2. Sodium carbonate solution is slowly added to the cooled solution. The soluti
June 2022, Unit 6, Q3(a)(iv) (3 marks): Ethanoic acid solution is added, drop by drop, to the neutralised mixture until the precipitate redissolves. Describe how the solution in the beaker should then
June 2022, Unit 6, Q4(a)(i) (1 mark): Label the diagram to show the direction of the water flow in the condenser. (1)
June 2022, Unit 6, Q4(a)(ii) (1 mark): Give a reason for using steam distillation to extract limonene. (1)
June 2022, Unit 6, Q4(a)(iii) (1 mark): The distillate may be collected in a pear‑shaped flask. Complete a labelled diagram showing the distillate. You should show clearly the limonene layer. (1)
January 2022, AS Unit 3, Q1(b)(i) (2 marks): Give two reasons why the student stirred the solution in Steps 3 and 4. (2)
January 2022, AS Unit 3, Q1(b)(ii) (2 marks): Use the graph to determine the maximum temperature change, ΔT, in this experiment. You must show your working on the graph. (2)
January 2022, AS Unit 3, Q1(b)(iii) (3 marks): Another student carried out the experiment using a polystyrene cup in place of the glass beaker. Explain how this student’s graph would be different. You may an
January 2022, AS Unit 3, Q1(c)(ii) (2 marks): The total percentage uncertainty in this experiment was 2.6 %. Show that the enthalpy change of 14.5 kJ mol–1 is consistent with a data book value of 14.8 kJ mo
January 2022, AS Unit 3, Q2(c) (3 marks): Compound X is converted into compound Y when refluxed with excess sodium dichromate(VI) in sulfuric acid. Compound Y is a liquid that is soluble in the reaction
January 2022, AS Unit 3, Q4(a)(i) (2 marks): Explain the purpose of the anhydrous calcium chloride. (2)
January 2022, AS Unit 3, Q4(a)(ii) (1 mark): Give the reason why granules of anhydrous calcium chloride are used rather than powder. (1)
January 2022, AS Unit 3, Q4(b)(i) (2 marks): Identify the main hazard related to chlorine gas, giving the best way of minimising the risk when using this gas. (2)
January 2022, AS Unit 3, Q4(b)(ii) (1 mark): Give a reason why the concentrated hydrochloric acid is added ‘drop by drop’ to the pear‑shaped flask. (1)
January 2022, AS Unit 3, Q4(c) (1 mark): Suggest why the heating of the aluminium in Step 3 is delayed by 20 s after the initial production of chlorine gas. (1)
January 2022, AS Unit 3, Q4(d) (1 mark): State how you would know the reaction is complete in Step 3. (1)
January 2022, AS Unit 3, Q4(e) (1 mark): Suggest the purpose of the potassium hydroxide in the absorption tube. (1)
January 2022, Unit 6, Q4(a) (2 marks): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
January 2022, Unit 6, Q4(d) (1 mark): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
January 2022, Unit 6, Q4(e)(i) (2 marks): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
January 2022, Unit 6, Q4(e)(ii) (1 mark): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
January 2022, Unit 6, Q4(f) (1 mark): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
January 2022, Unit 6, Q4(g) (2 marks): This question is about the preparation of phenylamine by the reduction of nitrobenzene. NH2 NO2 + 6[H] → + 2H2O phenylamine nitrobenzene Outline procedure Step
October 2021, AS Unit 3, Q2(b) (3 marks): Geraniol is extracted by steam distillation. water out vent to sink mixture to be steam distilled water water in HEAT HEAT collecting flask The steam distillati
October 2021, AS Unit 3, Q2(c) (3 marks): The geraniol will still contain small quantities of water. Describe how to produce a sample of pure, dry geraniol using a named drying agent. (3)
October 2021, AS Unit 3, Q2(d)(i) (2 marks): Complete the table to identify the hazards indicated by the symbols. (2)
October 2021, AS Unit 3, Q2(d)(ii) (1 mark): State one precaution, other than wearing safety spectacles and a laboratory coat, that should be taken when using pure geraniol to reduce the risk associated wi
October 2021, AS Unit 3, Q3(a) (3 marks): Plot a graph of temperature against time on the grid. (3)
October 2021, AS Unit 3, Q3(b) (2 marks): Determine the maximum temperature change, ΔT, using your graph. You must show your working on the graph. (2) ΔT =
October 2021, AS Unit 3, Q4(b) (2 marks): Evaluate the students' results and decide whether it is necessary to repeat their experiments. (2)
October 2021, AS Unit 3, Q5(c) (1 mark): Each reading of the burette has an uncertainty of ±0.05 cm3. Calculate the percentage uncertainty in Titration 4. (1)
October 2021, Unit 6, Q1(b) (2 marks): Describe a test, and its positive result, to confirm the presence of the sulfate ion in another sample of the copper(II) sulfate solution. (2)
October 2021, Unit 6, Q1(d)(ii) (1 mark): Name the most suitable piece of apparatus to measure the 10 cm3 of potassium iodide solution. (1)
October 2021, Unit 6, Q3(c) (1 mark): The thermometer used to measure the temperature change had an uncertainty of ±0.25 °C for each measurement. Calculate the percentage uncertainty in the temperat
October 2021, Unit 6, Q3(d) (5 marks): The temperature rise in this experiment was lower than expected, due to heat loss to the surroundings. Describe changes to the procedure that would give a more
October 2021, Unit 6, Q4(a) (3 marks): A student drew a diagram of the apparatus set up for distillation in Step 3. There are three errors in the diagram. Assume the apparatus is clamped correctly an
October 2021, Unit 6, Q4(c)(ii) (1 mark): State what should be done to separate the benzoic acid from the mixture produced in Step 4, before carrying out Step 5. (1)
October 2021, Unit 6, Q4(d) (1 mark): Describe the first stage in the recrystallisation process in Step 5. (1)
October 2021, Unit 6, Q4(e) (2 marks): The melting temperature of pure benzoic acid is 122 °C. State two ways in which the melting temperature changes if the benzoic acid is not pure. (2)
June 2021, AS Unit 3, Q3(c) (1 mark): Solid samples of soluble barium compounds such as barium oxide are toxic by inhalation due to the presence of barium ions. Give a safety precaution that should
June 2021, AS Unit 3, Q3(d) (1 mark): Barium also forms a peroxide. A bottle of barium peroxide has the hazard symbol Give the meaning of this symbol. (1)
June 2021, AS Unit 3, Q4(b)(i) (1 mark): State what must be added to the mixture in the flask before heating in Step 2. (1)
June 2021, AS Unit 3, Q4(b)(ii) (3 marks): Draw a labelled diagram of the apparatus that you would use to heat the mixture under reflux in Step 2. (3)
June 2021, AS Unit 3, Q4(c)(i) (1 mark): State why sodium hydrogencarbonate solution is added in Step 4. (1)
June 2021, AS Unit 3, Q4(c)(ii) (2 marks): Addition of sodium hydrogencarbonate solution in Step 4 causes vigorous effervescence. Explain how the problem associated with Step 4 should be dealt with. (2)
June 2021, AS Unit 3, Q4(c)(iii) (1 mark): Give the purpose of the anhydrous calcium chloride used in Step 5. (1)
June 2021, AS Unit 3, Q4(c)(iv) (1 mark): State how the appearance of the organic liquid would change in Step 5. (1)
June 2021, AS Unit 3, Q4(d) (1 mark): For the final distillation in Step 6, a thermometer with a scale giving readings to the nearest 1° C was provided. Give a suitable temperature range for the col
June 2021, Unit 6, Q1(b)(iv) (2 marks): When the mixture from (b)(iii) is warmed, a gas is evolved. Give a test to identify the gas stating the positive result of the test. (2)
June 2021, Unit 6, Q2(a) (1 mark): Give a reason why a measuring cylinder is more suitable than a graduated pipette for measuring the distilled water in Step 1. (1)
June 2021, Unit 6, Q2(c) (1 mark): Give the reason why Step 2 should be carried out in a fume cupboard. (1)
June 2021, Unit 6, Q2(d) (1 mark): Give the reason why the addition of ethanol in Step 3 results in the precipitation of crystals of Cu(NH3)4SO4.H2O. (1)
June 2021, Unit 6, Q2(e) (3 marks): Draw a labelled diagram of the apparatus used to filter the crystals under reduced pressure in Step 4. (3)
June 2021, Unit 6, Q2(f)(i) (1 mark): State the purpose of the ethanol in Step 5. (1)
June 2021, Unit 6, Q2(f)(ii) (1 mark): Give a reason why the ethanol is cold. (1)
June 2021, Unit 6, Q2(g)(ii) (1 mark): Suggest a reason why the apparent percentage yield in this preparation is often greater than 100 %. (1)
June 2021, Unit 6, Q3(c)(i) (1 mark): State what causes the initial stream of bubbles from the capillary tube in Step 3. (1)
June 2021, Unit 6, Q3(c)(ii) (1 mark): Suggest why the side-arm of the Thiele tube is heated, rather than point X on the diagram. (1)
June 2021, Unit 6, Q3(c)(iii) (1 mark): Suggest why mineral oil, and not water, is used in the Thiele tube when determining the boiling temperature of compound A. (1)
June 2021, Unit 6, Q3(c)(iv) (1 mark): Suggest why the results obtained when using this apparatus on different days may not be the same, even when no mistakes are made in carrying out the experiment.
January 2021, AS Unit 3, Q2(b)(ii) (2 marks): The diagram shows how the student read the filled pipette in Step 3. Identify the two mistakes the student made. (2) 25 cm3 ± 0.06 pipette B20 °C mark
January 2021, AS Unit 3, Q2(b)(iii) (2 marks): The student completely emptied the pipette for each transfer in Step 3. Explain the effect on the titre of completely emptying the pipette rather than leaving a
January 2021, AS Unit 3, Q3(b)(ii) (2 marks): The student suggested that the experiment could be made more accurate by increasing the mass of carbonate from 0.33 g to 1.00 g. No changes to the size of the a
January 2021, AS Unit 3, Q4(a)(i) (2 marks): The concentrated hydrochloric acid used in Step 1 was labelled Suggest two safety precautions, other than wearing safety spectacles and a laboratory coat, to mi
January 2021, AS Unit 3, Q4(a)(iii) (1 mark): State why the tap of the separating funnel must be opened in Step 3. (1)
January 2021, AS Unit 3, Q4(a)(iv) (1 mark): State why anhydrous sodium sulfate is added to the organic layer in Step 5. (1)
January 2021, AS Unit 3, Q4(a)(v) (4 marks): Draw the apparatus required to distil the product and collect the distillate between 50°C and 52°C in Step 6. (4)
January 2021, Unit 6, Q1(a)(i) (1 mark): Identify the hazard indicated by this label. (1)
January 2021, Unit 6, Q1(a)(ii) (2 marks): Describe how you would add small amounts of A until there is no further change. Name the apparatus you would use. (2)
January 2021, Unit 6, Q1(b)(ii) (1 mark): When A is added to C, vigorous effervescence occurs and the gas produced turns limewater cloudy. Identify, by name or formula, the gas produced. (1)
January 2021, Unit 6, Q1(b)(iii) (1 mark): Suggest the identity, by name or formula, of the anion in C. (1)
January 2021, Unit 6, Q1(b)(iv) (2 marks): Identify A by name or formula. Justify your answer. (2)
January 2021, Unit 6, Q1(b)(v) (2 marks): When A is added to D no change is seen. A small amount of this mixture is added to B and a white precipitate forms. Suggest what can be deduced about solutions
January 2021, Unit 6, Q2(a) (2 marks): Identify the main hazard in Step 1, giving a safety precaution that will reduce the risk. Assume that safety spectacles and a laboratory coat were used. (2)
January 2021, Unit 6, Q2(c) (2 marks): A student who used Method 1 obtained a value that was significantly larger than the actual concentration of the solution. Explain one possible source of experim
January 2021, Unit 6, Q3(a)(i) (1 mark): State why a reflux condenser is needed when the mixture is warmed. (1)
January 2021, Unit 6, Q3(a)(ii) (3 marks): Draw a diagram of the apparatus used to warm under reflux in this experiment. (3)
January 2021, Unit 6, Q3(a)(iii) (2 marks): Suggest why the reaction mixture is stirred continuously. (2)
January 2021, Unit 6, Q3(b) (1 mark): The excess acid is removed from the reaction mixture. The layer containing nitrobenzene is separated and dried before being purified by distillation. Identify a
January 2021, Unit 6, Q3(d)(i) (1 mark): State why a minimum volume of hot solvent is used in Step 1. (1)
January 2021, Unit 6, Q3(d)(ii) (1 mark): Explain why a preheated funnel is used in Step 2. (1)
January 2021, Unit 6, Q3(d)(iii) (2 marks): Give a reason for each of the two filtrations in Steps 2 and 3. (2)
January 2021, Unit 6, Q3(d)(iv) (1 mark): Give a possible reason why it is preferable to dry the solid in a desiccator rather than in an oven in Step 5. (1)
January 2021, Unit 6, Q3(e) (1 mark): The melting temperature of the recrystallised Organol Brown is measured to check its purity. State what you would observe if the sample was pure. (1)
October 2020, AS Unit 3, Q2(b) (6 marks): To identify the cations in sodium chloride and potassium carbonate, a student carried out flame tests using the following method. Step 1 A sample of solid sodi
October 2020, AS Unit 3, Q4(a)(ii) (1 mark): The diagram shows part of the thermometer when the temperature had reached its maximum. 30 20 Record the temperature in the table of results and then complete t
October 2020, AS Unit 3, Q5(a) (1 mark): Name a suitable piece of apparatus to measure the 25.0 cm3 of solution. (1)
October 2020, AS Unit 3, Q5(d) (3 marks): The titration was repeated without using an indicator. Describe how you would obtain large, dry crystals of the metal chloride, MCl, from this titration solutio
October 2020, Unit 6, Q3(a) (1 mark): Two of the hazard warning signs for phenol are State the most important hazard associated with phenol in this experiment and the precaution you would take to re
October 2020, Unit 6, Q3(e)(ii) (2 marks): Give two reasons why Run 1 has the lowest uncertainty in the volume measurements. (2)
October 2020, Unit 6, Q4(d) (3 marks): One student drew a diagram of the apparatus used for reflux in Step 4. water in water out anti-bumping granules heat Ide
October 2020, Unit 6, Q4(f) (2 marks): The filtration in Step 7 is carried out under reduced pressure. State two advantages of this method compared with ordina
October 2020, Unit 6, Q4(g) (2 marks): Describe how the purity of the recrystallised aspirin could be tested. Experimental details are not required. (2) (Total
January 2020, AS Unit 3, Q2(b)(i) (1 mark): The maximum uncertainty each time the thermometer was read was ± 0.1 °C. Calculate the percentage uncertainty in measuring the temperature change in this experi
January 2020, AS Unit 3, Q2(b)(ii) (2 marks): Suggest one way of reducing the percentage uncertainty in measuring the temperature change without changing the apparatus or just repeating the experiment. Just
January 2020, AS Unit 3, Q4(a) (2 marks): Step 1 5 cm3 of ethanol and 5 cm3 of water are added to a round-bottomed flask. The flask is placed in an ice bath and 5 cm3 of concentrated sulfuric acid is a
January 2020, AS Unit 3, Q4(c)(i) (3 marks): Draw a labelled diagram to show the apparatus suitable for this distillation. Include a thermometer but no clamps or stands. (3)
January 2020, AS Unit 3, Q4(c)(ii) (1 mark): State how anti-bumping granules prevent bumping in the distillation flask. (1)
January 2020, AS Unit 3, Q4(d)(ii) (1 mark): Describe how the aqueous layer could be removed from the separating funnel. (1)
January 2020, AS Unit 3, Q4(e) (1 mark): Step 5 After removing the aqueous layer, sodium hydrogencarbonate solution is added to the impure bromoethane in a separating funnel and the two layers separat
January 2020, AS Unit 3, Q4(f)(i) (1 mark): Identify, by name or formula, a suitable drying agent. (1)
January 2020, AS Unit 3, Q4(f)(ii) (1 mark): Describe how the appearance of the bromoethane changes after the drying agent has been added and the mixture allowed to stand. (1)
June 2019, AS Unit 3, Q1(c) (1 mark): Complete the diagram to show how you would collect the carbon dioxide obtained by heating ammonium carbonate, using another test tube as the only additional app
June 2019, AS Unit 3, Q2(b)(ii) (2 marks): One student said that if A was a primary alcohol this could be shown by oxidising it to the corresponding aldehyde and testing the product. Identify which appar
June 2019, AS Unit 3, Q2(b)(v) (2 marks): Another student said that if A was a secondary alcohol this could be shown by oxidising it to the corresponding ketone. Identify which apparatus (1, 2 or 3) sho
June 2019, AS Unit 3, Q2(c)(i) (2 marks): Give two reasons for the use of the mineral wool. (2)
June 2019, AS Unit 3, Q2(c)(ii) (2 marks): Explain why it is necessary to remove the delivery tube from the heated tube immediately when heating stops. (2)
June 2019, AS Unit 3, Q3(a)(i) (1 mark): Give a reason, other than preventing heat loss, for placing the polystyrene cup in a glass beaker. (1)
June 2019, AS Unit 3, Q3(a)(ii) (1 mark): Name the piece of apparatus suitable for measuring 50.0 cm3 of copper(II) sulfate solution. (1)
June 2019, AS Unit 3, Q3(a)(iii) (1 mark): Powdered metal reacts much faster than filings or granules. Suggest why this is important in this experiment. (1)
June 2019, AS Unit 3, Q3(b)(i) (3 marks): Plot a labelled graph of mass of metal on the horizontal axis against temperature change on the vertical axis. (3)
June 2019, AS Unit 3, Q3(b)(ii) (2 marks): Determine the mass of metal M that reacts exactly with 50.0 cm3 of 1.35 mol dm−3 copper(II) sulfate by drawing appropriate best-fit straight lines. You must sho
June 2019, AS Unit 3, Q3(b)(iv) (1 mark): One mass of M in the experiment gave an anomalous data point. Suggest a reason, other than measurement error, for this anomaly. (1)

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