plumiHow are chemicals separated and tested for purity?: OCR GCSE Chemistry B questions
Every OCR GCSE Chemistry B exam question on C5.1 How are chemicals separated and tested for purity?, 2018–2025, with its mark scheme and examiner’s report.
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Q4(a)(i)
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Q4(a)(ii)
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Q6(a)(ii)
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Q3(a)
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Q3(b)
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Q3(b)
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The whole paper ↗Q6(a)
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Q6(b)
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All 73 questions on How are chemicals separated and tested for purity?, as a list
- June 2025, Paper 1 Foundation, Q4(a)(i) (1 mark): What is the name of this type of mixture? Tick (✓) one box. Compound Element Formulation Pure [1]
- June 2025, Paper 1 Foundation, Q4(a)(ii) (1 mark): The table shows the percentage of each substance used in one type of cement. Substance Percentage (%) Calcium oxide 91.5 Magnesium oxide 3.5 Water Calculate the
- June 2025, Paper 1 Foundation, Q4(a)(iii) (1 mark): Cement can be harmful to skin and eyes. State one safety precaution that must be taken when using cement. [1]
- June 2025, Paper 1 Foundation, Q4(b)(i) (1 mark): The scientist thinks that dye B is a mixture. Explain how the results show that dye B is a mixture. [1]
- June 2025, Paper 1 Foundation, Q4(b)(ii) (2 marks): Calculate the Rf value for the colour used in dye A. Use the formula: Rf = distance moved by substance distance moved by solvent Rf = [2]
- June 2025, Paper 1 Foundation, Q4(b)(iii) (1 mark): Paper chromatography uses two phases. The mobile phase is the solvent. What is the name of the other phase? Tick (✓) one box. Separation Solute Stationary [1]
- June 2025, Paper 1 Foundation, Q5(c)(ii) (1 mark): Diamond is a pure substance. Explain what is meant by a pure substance. [1]
- June 2025, Paper 1 Foundation, Q6(a)(ii) (1 mark): The copper hydroxide produced in the reaction is insoluble in water. Name the process used to remove the copper hydroxide from the water. [1]
- June 2024, Paper 2 Foundation, Q3(a) (2 marks): Which statements about formulations are true and which are false? Tick (3) one box in each row. True False Formulations are a mixture of substances. Formulation
- June 2024, Paper 2 Foundation, Q3(b) (2 marks): The scientist uses distilled water for their medicines. They use simple distillation to distil tap water. What changes happen during simple distillation? Tick (
- June 2024, Paper 2 Foundation, Q3(c) (1 mark): Another worker says that tap water is already pure because it has been treated to kill bacteria. Explain why tap water is not a pure substance. [1]
- June 2024, Paper 2 Foundation, Q3(d) (2 marks): The scientist uses paper chromatography to separate the substances in one of their medicines. The diagram shows their results. Chromatography paper Beaker Start
- June 2024, Paper 2 Foundation, Q3(e) (2 marks): The scientist measures the melting point of some of the substances they use to make medicines. The table below shows their results. Substance Melting point (°C)
- June 2024, Paper 3 Higher, Q3(a) (1 mark): Explain why hexane rather than water must be used as the solvent for these dyes. [1]
- June 2024, Paper 3 Higher, Q3(b) (4 marks): Calculate the Rf value of dye B. Give the answer to an appropriate number of significant figures. Rf value = [4]
- June 2024, Paper 3 Higher, Q3(c) (1 mark): The student wants to check that there are no colourless substances in the dyes. What must be sprayed onto the chromatogram so any colourless substances can be s
- June 2024, Paper 4 Higher, Q6(a) (1 mark): Which statement is the definition of a formulation? Tick (3) one box. A mixture that contains definite proportions of substances. A solid substance that is solu
- June 2024, Paper 4 Higher, Q6(b) (2 marks): The scientist uses water to make up their medicines. In their laboratory they have distilled water and tap water. Explain why distilled water is pure and tap wa
- June 2024, Paper 4 Higher, Q6(c)(i) (2 marks): Identify the stationary phase and the mobile phase in their experiment. Stationary phase Mobile phase [2]
- June 2024, Paper 4 Higher, Q6(c)(ii) (2 marks): Use ideas about solubility to explain why the substances separate. [2]
- June 2024, Paper 4 Higher, Q6(c)(iii) (1 mark): The scientist wants to improve the chromatography experiment. Suggest one way they can increase the separation of the substances. [1]
- June 2024, Paper 4 Higher, Q6(d) (2 marks): The scientist measures the melting point of some of the substances they use to make medicines. The table shows their results. Substance Melting point (°C) A 102
- June 2023, Paper 1 Foundation, Q2(b) (2 marks): Alex heats 500 cm3 of the mineral water to make it more concentrated. Draw a labelled diagram of the apparatus that Alex uses. [2]
- June 2023, Paper 2 Foundation, Q10(b)(i) (2 marks): Calculate the Rf value of food colour D. Rf value = [2]
- June 2023, Paper 2 Foundation, Q10(b)(ii) (2 marks): Which safe food colours, A, B, C and D, are pure? Explain your answer. Food colours Explanation [2]
- June 2023, Paper 2 Foundation, Q10(b)(iii) (2 marks): Which two safe food colours have been used to make sweet 2? Tick (3) two boxes. A B C D [2]
- June 2023, Paper 2 Foundation, Q10(b)(iv) (1 mark): Ali says that he cannot be sure that the food colours used in sweet 1 are safe. Explain why Ali is correct. [1]
- June 2023, Paper 3 Higher, Q5(a)(i) (2 marks): Draw a labelled diagram of the equipment that Alex uses. [2]
- June 2023, Paper 4 Higher, Q2(b)(i) (2 marks): Calculate the Rf value of food colour D. Rf value = [2]
- June 2023, Paper 4 Higher, Q2(b)(ii) (2 marks): Which safe food colours, A, B, C and D, are pure? Explain your answer. Food colours Explanation [2]
- June 2023, Paper 4 Higher, Q2(b)(iii) (2 marks): Which two safe food colours have been used to make sweet 2? Tick (3) two boxes. A B C D [2]
- June 2023, Paper 4 Higher, Q2(b)(iv) (1 mark): Ali says that he cannot be sure that the food colours used in sweet 1 are safe. Explain why Ali is correct. [1]
- June 2022, Paper 1 Foundation, Q10(a)(i) (1 mark): Complete the sentence to explain why graphite can be separated by filtering it out. Use one word from the list. aqueous insoluble non-aqueous soluble Graphite c
- June 2022, Paper 1 Foundation, Q10(a)(ii) (2 marks): Jamal is using mixtures and pure substances. Complete Table 10.1 to identify which are mixtures and which are pure substances. Tick (✓) one box in each row. Pur
- June 2022, Paper 2 Foundation, Q2(b) (2 marks): At the end of the reaction, the boiling tube contains a mixture of a precipitate of copper hydroxide in a solution. Describe how Jane can separate pure, dry cop
- June 2022, Paper 2 Foundation, Q4(a) (3 marks): Use the graph to describe how temperature affects the solubility of sodium chloride and potassium chloride. Use values from the graph to support your answer. [3
- June 2022, Paper 2 Foundation, Q4(b)(i) (2 marks): Use Jack’s formula to predict the solubility of potassium chloride at 80 °C. predicted solubility of potassium chloride at 80 °C = g in 100 g water [2]
- June 2022, Paper 2 Foundation, Q4(b)(ii) (2 marks): Does this value agree with the solubility of potassium chloride at 80 °C shown on the graph? Yes No Use data from the graph to explain your answer. [2]
- June 2022, Paper 2 Foundation, Q4(c) (6 marks): The solubility of a salt shows how much salt dissolves in 100 g of water. The graph shows the solubility of some Group 1 salts in water at different temperature
- June 2022, Paper 3 Higher, Q12(a) (2 marks): Eve says, ‘Copper sulfate is a mixture of several elements. It is not a pure substance.’ Explain why Eve is wrong. [2]
- June 2022, Paper 4 Higher, Q7(b)(i) (2 marks): Describe how she can separate pure copper hydroxide from the final mixture. [2]
- June 2022, Paper 4 Higher, Q7(b)(ii) (2 marks): Jane leaves the copper hydroxide to dry in a warm oven. After 30 minutes she weighs the copper hydroxide on a balance. Jane is not sure if the copper hydroxide
- November 2021, Paper 1 Foundation, Q4(a)(i) (1 mark): Amaya starts by drawing a line on a piece of filter paper using ink. Describe one way in which Amaya can improve this part of her method. [1]
- November 2021, Paper 1 Foundation, Q4(a)(ii) (1 mark): Give one reason for your answer to (a)(i). [1]
- November 2021, Paper 1 Foundation, Q4(b)(i) (1 mark): Each sweet contains a mixture of dyes. How many different dyes are there in all of the sweets that Sundip has used? Use the chromatogram. Total number of differ
- November 2021, Paper 1 Foundation, Q4(b)(ii) (1 mark): Which dye is the least soluble in the solvent? [1]
- November 2021, Paper 1 Foundation, Q4(b)(iii) (1 mark): Give one reason for your answer to (b)(ii). [1]
- November 2021, Paper 1 Foundation, Q4(b)(iv) (1 mark): Rf values can be calculated using this equation: distance moved by dye Rf = distance moved by solvent front Which dye has the largest Rf value? [1]
- November 2021, Paper 1 Foundation, Q4(c) (3 marks): Ali has a mixture of carbon and copper sulfate crystals. Carbon is insoluble in water. Complete the list to show the correct order of methods he needs to obtain
- November 2021, Paper 3 Higher, Q7(a)(i) (1 mark): Identify the mistake in Amaya’s method. [1]
- November 2021, Paper 3 Higher, Q7(a)(ii) (1 mark): Why will this mistake stop Amaya from getting useful results? [1]
- November 2021, Paper 3 Higher, Q7(b)(i) (2 marks): Amaya says, ‘The chromatogram shows that there were a total of four different pure dyes used in the three sweets.’ Explain why this is incorrect. [2]
- November 2021, Paper 3 Higher, Q7(b)(ii) (1 mark): Which dye is the most soluble in water? [1]
- November 2021, Paper 3 Higher, Q7(b)(iii) (1 mark): Give one reason for your answer to (b)(ii). [1]
- November 2021, Paper 3 Higher, Q7(b)(iv) (2 marks): Calculate the Rf value for the yellow dye. Use the chromatogram and the equation: distance travelled by solute Rf = distance travelled by solvent front Rf value
- November 2021, Paper 3 Higher, Q7(c) (3 marks): Ali has a mixture of carbon in copper sulfate solution. Carbon is insoluble in water. Describe a method Ali can use to obtain pure copper sulfate crystals from
- November 2020, Paper 1 Foundation, Q9(d) (2 marks): Ammonium sulfate is mixed with other compounds to make the fertiliser Moregrow. Moregrow is a white powder. Sundip and Jack talk about the compounds in Moregrow
- June 2019, Paper 1 Foundation, Q12(a)(i) (1 mark): Which of the three solvents are non-aqueous? [1]
- June 2019, Paper 1 Foundation, Q12(a)(ii) (1 mark): Ben uses paper chromatography to investigate the dye. Which of the three solvents should Ben use in his investigation? [1]
- June 2019, Paper 1 Foundation, Q12(b)(i) (1 mark): Name the stationary phase. [1]
- June 2019, Paper 1 Foundation, Q12(b)(ii) (2 marks): What is wrong with the way Ben set up his experiment? Explain your answer. [2]
- June 2019, Paper 1 Foundation, Q12(b)(iii) (2 marks): Which spot has the greatest Rf value in the chromatogram at the end? Explain your answer. [2]
- June 2019, Paper 1 Foundation, Q12(c) (1 mark): Ben thinks the dye is a pure substance. Kareem, another student, disagrees. Who do you agree with? Explain your answer. [1]
- June 2019, Paper 1 Foundation, Q12(d) (1 mark): Ben measures the melting point of the dye. Describe what Ben would see if the dye is pure. [1]
- June 2019, Paper 3 Higher, Q2(a)(i) (1 mark): Which of the three solvents are non-aqueous? [1]
- June 2019, Paper 3 Higher, Q2(a)(ii) (1 mark): Ben uses paper chromatography to investigate the dye. Which of the three solvents should Ben use in his investigation? [1]
- June 2019, Paper 3 Higher, Q2(b)(i) (1 mark): Name the stationary phase. [1]
- June 2019, Paper 3 Higher, Q2(b)(ii) (2 marks): What is wrong with the way Ben set up his experiment? Explain your answer. [2]
- June 2019, Paper 3 Higher, Q2(b)(iii) (2 marks): Which spot has the greatest Rf value in the chromatogram at the end? Explain your answer. [2]
- June 2019, Paper 3 Higher, Q2(c) (1 mark): Ben thinks the dye is a pure substance. Kareem, another student, disagrees. Who do you agree with? Explain your answer. [1]
- June 2019, Paper 3 Higher, Q2(d) (1 mark): Ben measures the melting point of the dye. Describe what Ben would see if the dye is pure. [1]
- June 2018, Paper 1 Foundation, Q3(c)(ii) (1 mark): Alex wants to make solid ammonium sulfate from the solution of ammonium sulfate. What would Alex do first? Tick (3) one box. Distil the solution. Evaporate the
- June 2018, Paper 2 Foundation, Q6(b)(i) (2 marks): Amir uses different techniques to separate solid copper oxide and to obtain crystals of copper chloride from the mixture. Draw lines from each substance to the
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