Acids, bases and salt preparations: Edexcel International GCSE Chemistry questions

Every Edexcel International GCSE Chemistry exam question on Acids, bases and salt preparations (specification points 2.34–2.43), 2019–2025, with its mark scheme and examiner’s report.

All 105 questions on Acids, bases and salt preparations, as a list

June 2025, Paper 2, Q3(b) (1 mark): Which of these compounds is an insoluble solid? (1) A calcium nitrate B calcium sulfate C magnesium nitrate D magnesium sulfate
June 2025, Paper 2, Q5(d)(ii) (4 marks): The student repeats the titration without the methyl orange indicator. They add exactly 26.50 cm3 of sulfuric acid to the potassium hydroxide solution. Describe
June 2025 (R), Paper 1, Q6(a) (1 mark): How does hydrochloric acid behave when acting as an acid? (1) A as an electron acceptor B as an electron donor C as a proton acceptor D as a proton donor
June 2025 (R), Paper 1, Q6(b) (1 mark): State one observation made during this reaction. (1)
June 2025 (R), Paper 1, Q6(c) (1 mark): Give a reason why the student adds an excess of magnesium to the dilute hydrochloric acid. (1)
June 2025 (R), Paper 1, Q6(d) (5 marks): Describe what the student should do to the mixture formed in (c) to produce pure, dry crystals of hydrated magnesium chloride. (5)
June 2025 (R), Paper 2, Q3(a)(i) (1 mark): Give the meaning of the term saturated solution. (1)
June 2025 (R), Paper 2, Q3(a)(ii) (1 mark): Give a reason why crystals form when the saturated solution cools from 50 °C to room temperature. (1)
June 2025 (R), Paper 2, Q3(b) (2 marks): The teacher pours 25 cm3 of a saturated solution of potassium permanganate at room temperature into an evaporating dish. The teacher leaves the solution until a
June 2025 (R), Paper 2, Q6(c)(iii) (3 marks): Describe how the student can obtain a pure, dry sample of calcium phosphate from the mixture at the end of the reaction. (3)
November 2024, Paper 2, Q5(c) (5 marks): This is the equation for the reaction between dilute nitric acid and sodium hydroxide solution. HNO3(aq) + NaOH(aq) → NaNO3(aq) + H2O(l) After the titration, th
June 2024, Paper 2, Q4(a)(i) (2 marks): Plot the data for potassium nitrate and for sodium nitrate on the grid. (2)
June 2024, Paper 2, Q4(a)(ii) (2 marks): Draw and label a curve of best fit for KNO3 and for NaNO3 (2) 45 40 35 30 25 Mass of solute in g 20 15 10 5 0 10 20 30 40 50 60 70 80 Temperature in °C
June 2024, Paper 2, Q4(b) (1 mark): The graph shows the temperature at which the maximum mass dissolved is the same for each solute. Determine this temperature. (1) temperature = °C
June 2024, Paper 2, Q4(c) (2 marks): Use your graph to calculate the solubility, in g per 100 g of water, of sodium nitrate at 30 °C. [1.0 cm3 of water has a mass of 1.0 g] (2) solubility of sodium
June 2024, Paper 2, Q4(d) (3 marks): 25 cm3 of a saturated solution of potassium nitrate is cooled from 50 °C to 20 °C. Use your graph to determine the mass, in grams, of potassium nitrate that cry
June 2024, Paper 2, Q6(a) (3 marks): Describe how the scientist could obtain a pure dry sample of lead(II) bromide (PbBr2) from the reaction mixture. (3)
June 2024 (R), Paper 2, Q3(c)(ii) (1 mark): Give a reason why the student adds an excess of magnesium in step 3. (1)
June 2024 (R), Paper 2, Q5(b) (4 marks): The student repeats the titration without the indicator and forms a solution of sodium sulfate. Describe how the student can obtain pure, dry crystals of hydrat
November 2023, Paper 1, Q10(a) (1 mark): State why the mixture is filtered. (1)
November 2023, Paper 1, Q10(b) (4 marks): Describe how a pure, dry sample of hydrated zinc nitrate crystals could be obtained from the filtrate. (4)
June 2023, Paper 1, Q6(a)(i) (1 mark): Complete the equation for the reaction by adding the state symbols. (1) Pb(NO3)2 ( ) + 2KCl ( ) → PbCl2 ( ) + 2KNO3 ( )
June 2023, Paper 1, Q6(b)(i) (1 mark): Plot the results on the grid. (1)
June 2023, Paper 1, Q6(b)(ii) (1 mark): Draw a circle around the anomalous result. (1)
June 2023, Paper 1, Q6(b)(iii) (2 marks): Draw a line of best fit through the first four points and another line of best fit through the last three points. Make sure that the lines cross. (2) 4.0 3.0 He
June 2023, Paper 1, Q6(b)(iv) (2 marks): Give two possible mistakes the student could have made to cause the anomalous result. (2) 1 2
June 2023, Paper 1, Q6(b)(v) (1 mark): State why the first line of best fit should pass through the origin. (1)
June 2023, Paper 1, Q6(b)(vi) (1 mark): Use your graph to determine the volume of lead(II) nitrate solution needed to react completely with 15.0 cm3 of potassium chloride solution. (1) volume = cm3
June 2023, Paper 2, Q2(b)(ii) (1 mark): Which colour change occurs when copper(II) carbonate is heated? (1) A blue to black B blue to orange C green to black D green to orange
June 2023 (R), Paper 2, Q5(a) (4 marks): Describe how solutions of lead nitrate and potassium bromide can be used to make a pure, dry sample of lead(II) bromide. (4)
June 2023 (R), Paper 2, Q5(c)(i) (1 mark): Plot the student’s results on the grid. (1)
June 2023 (R), Paper 2, Q5(c)(ii) (1 mark): Draw a line of best fit, ignoring the anomalous result. (1) 10.00 9.80 9.60 Electrical conductivity in arbitrary units 9.40 9.20 9.00 0 10 20 30 40 50 Total vol
June 2023 (R), Paper 2, Q5(c)(iii) (2 marks): Explain the shape of the graph. (2)
June 2023 (R), Paper 2, Q5(c)(iv) (1 mark): Suggest a mistake the student could have made to cause the anomalous result. (1)
June 2023 (R), Paper 2, Q5(c)(v) (1 mark): Further 10 cm3 volumes of lead(II) nitrate are added to the beaker so the lead(II) nitrate is in excess. Predict what will happen to the conductivity of the mix
January 2023, Paper 1, Q11(a)(i) (2 marks): Explain why it is important that magnesium is in excess. (2)
January 2023, Paper 1, Q11(a)(iii) (5 marks): Describe how the student can obtain dry crystals of hydrated magnesium nitrate from the mixture at the end of the reaction. (5)
January 2023, Paper 2, Q3(a) (1 mark): Which pair of solutions produces an insoluble salt when mixed? (1) A sodium sulfate and potassium nitrate B potassium carbonate and calcium nitrate C sodium chl
January 2023, Paper 2, Q3(b) (3 marks): When solutions of lead nitrate and sodium sulfate are mixed, one product is solid lead sulfate. This is the equation for the reaction. Pb(NO3)2(aq) + Na2SO4(aq)
January 2023, Paper 2, Q3(c)(i) (1 mark): Plot the points on the grid. (1)
January 2023, Paper 2, Q3(c)(ii) (1 mark): Draw a curve of best fit. (1) 160 140 120 100 Solubility in g per 100 g of water 80 60 40 20 0 0 20 40 60 80 100 Temperature in °C
January 2023, Paper 2, Q3(c)(iii) (2 marks): A saturated solution of the salt in 100 g of water is cooled from 90 °C to 30 °C. Use your graph to determine the mass of salt that will crystallise. Show your
January 2023 (R), Paper 1, Q9(b)(i) (1 mark): State why the student uses an excess of zinc powder. (1)
January 2023 (R), Paper 1, Q9(b)(ii) (5 marks): Describe what the student should do next to obtain pure, dry crystals of zinc nitrate. (5)
January 2023 (R), Paper 2, Q2(a) (1 mark): State one other factor that affects the solubility. (1)
January 2023 (R), Paper 2, Q2(b)(i) (2 marks): The flowchart shows the correct order of some of the steps. Complete the flowchart by putting the remaining steps in the correct order. (2) F B D E
January 2023 (R), Paper 2, Q2(b)(ii) (2 marks): These are the student’s results. mass of empty evaporating basin = 60.5 g mass of evaporating basin and dry salt = 78.1 g Calculate the solubility of the salt i
June 2022, Paper 2, Q2(d) (1 mark): State why sulfuric acid would not be a suitable acid to use in this titration. (1)
June 2022 (R), Paper 2, Q6(d) (4 marks): The student plans to obtain pure dry crystals of hydrated sodium sulfate. They add the calculated volume of sulfuric acid to 25.0 cm3 of the sodium hydroxide so
January 2022, Paper 1, Q7(a) (1 mark): Different solutions are mixed in separate test tubes. Tube 1 copper(II) sulfate solution and calcium chloride solution Tube 2 magnesium nitrate solution and pot
January 2022, Paper 1, Q7(b)(ii) (5 marks): The student wants to obtain pure, dry crystals of sodium nitrate. Crystals of sodium nitrate decompose at temperatures above 300 °C. Describe a method the stude
January 2022, Paper 1, Q7(b)(iii) (1 mark): Give an advantage of mixing solutions containing equal amounts, in moles, of silver nitrate and sodium chloride. (1)
January 2022, Paper 2, Q3(a)(i) (2 marks): Determine the temperature at which copper(II) chloride and sodium chloride have the same solubility. Show on the graph how you obtained your answer. (2) tempera
January 2022, Paper 2, Q3(a)(ii) (2 marks): A saturated solution of copper(II) chloride in 100 g of water is cooled from 40 °C to 10 °C. Determine the mass, in grams, of copper(II) chloride that crystalli
January 2022, Paper 2, Q3(b)(i) (1 mark): Calculate the mass of dry potassium chloride obtained. (1) mass = g
January 2022, Paper 2, Q3(b)(ii) (1 mark): Calculate the mass of water removed. (1) mass = g
January 2022, Paper 2, Q3(b)(iii) (2 marks): Calculate the solubility of potassium chloride in grams per 100 grams of water. (2) solubility = g per 100 g of water
January 2022 (R), Paper 1, Q1(f) (2 marks): Name the two products of the reaction between hydrochloric acid and potassium hydroxide. (2) 1 2
January 2022 (R), Paper 2, Q6(a) (3 marks): Describe what the teacher should do next to obtain a pure, dry sample of lead(II) bromide. (3)
November 2021, Paper 1, Q8(a) (6 marks): Barium chloride can be made by reacting barium carbonate with dilute hydrochloric acid. The chemical equation for the reaction is BaCO3(s) + 2HCl(aq) → BaCl2(aq
November 2021, Paper 2, Q2(a) (2 marks): The box lists words that may be used to explain the term saturated solution. solute solvent temperature Explain, using all the words in the box, the term satura
November 2021, Paper 2, Q2(b)(i) (1 mark): Name the piece of apparatus that the student should use in Step 2 to measure exactly 10.0 cm3 of pure water. (1)
November 2021, Paper 2, Q2(b)(ii) (1 mark): Suggest why the boiling tube is not heated directly using a Bunsen burner in Step 3. (1)
November 2021, Paper 2, Q2(b)(iii) (1 mark): Suggest how the student could improve the reliability of her recorded temperature in Step 5. (1)
November 2021, Paper 2, Q2(b)(iv) (2 marks): In Step 5, crystals start to form at 26 °C. Calculate the solubility of the solid, in g per 100 g of water, at 26 °C. [1.0 cm3 of pure water has a mass of 1.0 g
November 2021, Paper 2, Q2(c)(i) (1 mark): State the temperature when A and B have the same solubility. (1) temperature = °C
November 2021, Paper 2, Q2(c)(ii) (2 marks): Calculate the mass of B that will dissolve in 250 g of water at 60 °C. Show your working. (2) mass = g
November 2021, Paper 2, Q2(c)(iii) (1 mark): Suggest why the values for the solubility of A and B may be less accurate at 95 °C than at lower temperatures. (1)
June 2021, Paper 1, Q8(b)(ii) (1 mark): Write a chemical equation for the reaction of ammonia with sulfuric acid. (1)
June 2021, Paper 1, Q10(c)(i) (1 mark): Complete the equation for the reaction by adding the state symbols. (1) Pb(NO3)2( ) + 2HCl( ) → PbCl2( ) + 2HNO3( )
June 2021, Paper 2, Q4(a)(i) (1 mark): Plot the results on the grid. (1)
June 2021, Paper 2, Q4(a)(ii) (1 mark): Draw a circle around the anomalous result. (1)
June 2021, Paper 2, Q4(a)(iii) (1 mark): Ignoring the anomalous result, draw a curve of best fit. (1) 45 40 35 30 25 20 15 10 5 0 10 20 30 40 50 60 70 80 Temperature in oC
June 2021, Paper 2, Q4(b) (2 marks): Suggest two possible mistakes that could have caused the anomalous result. (2) 1 2
June 2021, Paper 2, Q4(c) (2 marks): Use your graph to find the maximum mass of potassium nitrate that dissolves in 25 cm3 of water at 75 oC. Show on your graph how you obtained your answer. (2) ma
June 2021, Paper 2, Q4(d) (2 marks): Use your graph to calculate the solubility of potassium nitrate in g per 100 g of water at 25 oC. [1.0 cm3 of water has a mass of 1.0 g] (2) solubility = g per
January 2021, Paper 1, Q6(a) (3 marks): When solutions of salts are mixed together, precipitates sometimes form. The insoluble salt barium carbonate forms as a precipitate when solutions of the solubl
January 2021, Paper 2, Q6(a) (4 marks): Describe how a student could prepare a pure, dry sample of silver chloride starting with copper(II) chloride solution and silver nitrate solution. (4)
January 2021, Paper 2, Q6(b)(i) (2 marks): Plot the student’s results. (2)
January 2021, Paper 2, Q6(b)(ii) (1 mark): Draw two straight lines of best fit, ignoring the anomalous result. (1) 4 3 Height of precipitate 2 in cm 1 0 0 1 2 3 4 5 6 7 8 Volume of silver nitrate added i
January 2021, Paper 2, Q6(b)(iii) (1 mark): Suggest a mistake the student made to cause the anomalous result. (1)
January 2021, Paper 2, Q6(b)(iv) (1 mark): Give a reason why the last three heights are the same. (1)
January 2021, Paper 2, Q6(c)(i) (1 mark): Name a piece of apparatus suitable for measuring 25.0 cm3 of copper(II) chloride solution. (1)
January 2021 (R), Paper 1, Q10(a)(i) (1 mark): State the name given to this type of reaction. (1)
January 2021 (R), Paper 1, Q10(a)(ii) (1 mark): State, in terms of protons, what happens in this reaction. (1)
January 2021 (R), Paper 1, Q10(b)(i) (5 marks): A student is given 50 cm3 of dilute sulfuric acid and a bottle of solid copper(II) carbonate. Describe the method that the student should use to prepare a satur
November 2020, Paper 1, Q10(c)(ii) (6 marks): A student is given a sample of solid red lead oxide and some dilute nitric acid. Describe how the student could obtain a pure dry sample of lead(II) nitrate cry
November 2020 (R), Paper 1, Q7(a)(i) (1 mark): Complete the equation for this reaction by giving the correct state symbols. (1) Zn ( ) + H2SO4 ( ) → ZnSO4 ( ) + H2 ( )
November 2020 (R), Paper 1, Q7(a)(ii) (1 mark): State what would be observed during this reaction. (1)
November 2020 (R), Paper 1, Q7(b)(i) (2 marks): Explain why it is necessary to add excess zinc. (2)
November 2020 (R), Paper 1, Q7(b)(ii) (2 marks): Draw a diagram of the apparatus the student should use to remove the unreacted zinc and collect the zinc sulfate solution. (2)
November 2020 (R), Paper 2, Q6(a) (1 mark): Name a suitable piece of apparatus that the student should use to measure 25.0 cm3 of sodium hydroxide solution. (1)
November 2020 (R), Paper 2, Q6(c)(i) (2 marks): Describe what the student should do next to prepare a pure solution of sodium chloride. (2)
November 2020 (R), Paper 2, Q6(c)(ii) (4 marks): Describe how the student could obtain dry crystals of sodium chloride from the pure sodium chloride solution. (4)
January 2020, Paper 2, Q7(b)(i) (5 marks): Describe how a pure, dry sample of the insoluble salt, barium sulfate, could be made from the two solids sodium sulfate and barium chloride. (5)
January 2020, Paper 2, Q7(b)(ii) (2 marks): Give an ionic equation for the reaction that occurs. Include state symbols in your equation. (2)
January 2020 (R), Paper 2, Q3(a) (1 mark): What term is used for this reaction? (1) A neutralisation B precipitation C redox D thermal decomposition
January 2020 (R), Paper 2, Q3(b) (2 marks): Give two more steps that will produce a pure, dry sample of silver chloride. (2) Step 4 Step 5
June 2019, Paper 1, Q14(a) (1 mark): State why the acid is warmed in stage 2. (1)
June 2019, Paper 1, Q14(b) (1 mark): State how the student would know that the copper(II) oxide is in excess in stage 4. (1)
June 2019, Paper 1, Q14(c) (1 mark): State why the mixture is filtered in stage 5. (1)
June 2019, Paper 1, Q14(d) (1 mark): State the colour of the filtrate obtained in stage 5. (1)
June 2019, Paper 1, Q14(e) (5 marks): Describe how the student could obtain a pure, dry sample of hydrated copper(II) sulfate crystals from the filtrate in stage 6. (5)
June 2019 (R), Paper 1, Q7(a)(ii) (6 marks): A student has a beaker containing dilute nitric acid. Describe a method that she could use to prepare a pure, dry sample of magnesium nitrate crystals from magn
June 2019 (R), Paper 1, Q8(a)(i) (1 mark): Give a word equation for this neutralisation reaction. (1)

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