plumiHow are chemicals separated and tested for purity?: OCR GCSE Combined Science B questions
Every OCR GCSE Combined Science 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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Q6(a)
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Q6(b)(i)
The whole paper ↗Q6(b)(ii)
The whole paper ↗Q6(c)
The whole paper ↗Q6(d)
The whole paper ↗Q5(a)(i)
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Q5(a)(ii)
The whole paper ↗Q5(a)(iii)
The whole paper ↗Q5(b)
The whole paper ↗Q5(c)(i)
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Q5(c)(ii)
The whole paper ↗Q5(d)(i)
The whole paper ↗Q5(d)(ii)
The whole paper ↗Q5(d)(iii)
The whole paper ↗Q11(a)
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Q11(b)
The whole paper ↗Q11(c)(i)
The whole paper ↗Q11(c)(ii)
The whole paper ↗Q11(d)(i)
The whole paper ↗Q11(d)(ii)
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All 57 questions on How are chemicals separated and tested for purity?, as a list
- June 2025, Combined Science Paper 4 Foundation, Q6(a) (2 marks): The student sets up the experiment as shown in the diagram. Lid Beaker Chromatography paper Start line drawn in ink Solvent A B X Identify two mistakes that the
- June 2025, Combined Science Paper 4 Foundation, Q6(b)(i) (3 marks): Ink Sample X is a mixture. One of the substances in Ink Sample X travels 24 mm on the chromatogram. The solvent travels 39 mm. Calculate the Rf value of this su
- June 2025, Combined Science Paper 4 Foundation, Q6(b)(ii) (1 mark): How could you conclude from the chromatogram that Ink Sample X is a mixture? [1]
- June 2025, Combined Science Paper 4 Foundation, Q6(c) (1 mark): Another substance in Ink Sample X does not travel up the chromatography paper. Suggest one change to the experiment that would cause this substance to travel up
- June 2025, Combined Science Paper 4 Foundation, Q6(d) (1 mark): Ink Sample B is also a mixture. All of the components of Ink Sample B have similar solubility in the solvent, but have different boiling points. Explain why sim
- June 2025, Chemistry Paper 6 Higher, Q5(a)(i) (6 marks): The scientist decides to use paper chromatography to test the samples. The diagram shows the results for one of the samples. (i)* Describe how the scientist use
- June 2025, Chemistry Paper 6 Higher, Q5(a)(ii) (1 mark): The scientist says that the results show that the sample is impure. Explain why they are correct. [1]
- June 2025, Chemistry Paper 6 Higher, Q5(a)(iii) (1 mark): The scientist wants to increase the distance between the spots on the chromatogram. How can the method be adapted to increase the distance between the spots? Ti
- June 2025, Chemistry Paper 6 Higher, Q5(b) (1 mark): What other method could the scientist use to check the purity of the solid samples? [1]
- June 2024, Chemistry Paper 2 Foundation, Q5(c)(i) (1 mark): What does a scientist mean by a pure substance? Tick (✓) one box. It contains only one element or compound. It contains only one type of atom. It does not conta
- June 2024, Chemistry Paper 2 Foundation, Q5(c)(ii) (1 mark): How does the melting point of a substance show if it is pure? [1]
- June 2024, Chemistry Paper 2 Foundation, Q5(d)(i) (3 marks): Draw lines to connect each letter with its correct label. Letter Label A Chromatography Paper B Solvent C Solvent Front D Starting Line [3]
- June 2024, Chemistry Paper 2 Foundation, Q5(d)(ii) (1 mark): How would the results of this experiment show that a substance was pure? [1]
- June 2024, Chemistry Paper 2 Foundation, Q5(d)(iii) (1 mark): What step is needed if the substance being tested is colourless? Tick (✓) one box. Use a locating agent at the end. Use a second piece of paper. Use an extra so
- June 2023, Chemistry Paper 2 Foundation, Q11(a) (2 marks): A representative for Healthyfood says that the food colouring is pure. A scientist says that it is not pure. Explain the different meanings of the word ‘pure’ u
- June 2023, Chemistry Paper 2 Foundation, Q11(b) (1 mark): The table shows the melting points of some substances. Substance Melting point (°C) A 42 B 60–66 C 92–98 D 104 Which two substances are chemically pure? and [1]
- June 2023, Chemistry Paper 2 Foundation, Q11(c)(i) (2 marks): Draw lines to connect each letter with its correct label. A Mobile phase B Solvent front C Stationary phase [2]
- June 2023, Chemistry Paper 2 Foundation, Q11(c)(ii) (1 mark): Which property causes the dyes in the food colouring to separate? Tick (3) one box. Their different boiling points. Their different colours. Their different dis
- June 2023, Chemistry Paper 2 Foundation, Q11(d)(i) (2 marks): Measure the distance moved by dye 1 and by the solvent. Use a ruler. Distance moved by dye 1 = cm Distance moved by solvent = cm [2]
- June 2023, Chemistry Paper 2 Foundation, Q11(d)(ii) (2 marks): Calculate the Rf value of dye 1. Use this formula. Rf = distance moved by the dye (cm) distance moved by the solvent (cm) Rf = [2]
- June 2023, Chemistry Paper 6 Higher, Q2(a) (2 marks): A representative for Healthyfood says that the food colouring is pure. A scientist says that it is not pure. Explain the different meanings of the word ‘pure’ u
- June 2023, Chemistry Paper 6 Higher, Q2(b) (1 mark): The table shows the melting points of some substances. Substance Melting point (°C) A 42 B 60–66 C 92–98 D 104 Which two substances are chemically pure? and [1]
- June 2023, Chemistry Paper 6 Higher, Q2(c)(i) (2 marks): Draw lines to connect each letter with its correct label. A Mobile phase B Solvent front C Stationary phase [2]
- June 2023, Chemistry Paper 6 Higher, Q2(c)(ii) (1 mark): Which property causes the dyes in the food colouring to separate? Tick (3) one box. Their different boiling points. Their different colours. Their different dis
- June 2023, Chemistry Paper 6 Higher, Q2(d)(i) (2 marks): Measure the distance moved by dye 1 and by the solvent. Use a ruler. Distance moved by dye 1 = cm Distance moved by solvent = cm [2]
- June 2023, Chemistry Paper 6 Higher, Q2(d)(ii) (2 marks): Calculate the Rf value of dye 1. Use this formula. Rf = distance moved by the dye (cm) distance moved by the solvent (cm) Rf = [2]
- June 2022, Chemistry Paper 2 Foundation, Q5(a) (4 marks): Complete the sentence to describe how chromatography works. Use words from the list. condensed distributed dyes mobile paper solvent stationary The in the mixtu
- June 2022, Chemistry Paper 2 Foundation, Q5(b) (3 marks): Rf values are used to identify dyes. They are calculated using this equation: distance moved by the substance Rf = distance moved by the solvent The Rf value of
- June 2022, Chemistry Paper 2 Foundation, Q5(c) (6 marks): Paper chromatography can be used to identify dyes in a mixture. (c)* A student checks the Rf value of sunshine yellow using chromatography. The chromatogram pro
- November 2021, Chemistry Paper 2 Foundation, Q8(e)(i) (1 mark): Tablets are an example of a type of substance called a formulation. Complete the sentences to describe a formulation. Put a ring around the correct answers. A f
- November 2021, Chemistry Paper 2 Foundation, Q8(e)(ii) (1 mark): Which method can be used to show if a substance is pure or impure? Tick (✓) one box. Chromatography Combustion Measurement of pH Neutralisation [1]
- November 2020, Chemistry Paper 2 Foundation, Q3(d) (2 marks): Sodium chloride is soluble in water. Sodium chloride crystals can be made from a solution of sodium chloride in water by the process of crystallisation. Which t
- November 2020, Chemistry Paper 6 Higher, Q3(b)(i) (2 marks): The melting point of a substance can be used to test its purity. Ben measures the melting point of an aspirin tablet and compares his results with the melting p
- November 2020, Chemistry Paper 6 Higher, Q3(b)(ii) (1 mark): Which other experiment can Ben use to find out whether his sample of aspirin is pure? Tick (3) one box. Dissolve the aspirin in water Use paper chromatography D
- June 2019, Chemistry Paper 2 Foundation, Q2(a) (3 marks): Complete the sentences to explain how solid salt forms. Put a ring around each correct choice to complete the sentences. The heat / light from the sun decreases
- June 2019, Chemistry Paper 2 Foundation, Q2(b)(i) (3 marks): Put the steps in the correct order. B [3]
- June 2019, Chemistry Paper 2 Foundation, Q2(b)(ii) (2 marks): Jack finds that his method makes very small crystals. How could he change step D so that he makes larger crystals? [2]
- June 2019, Chemistry Paper 2 Foundation, Q2(b)(iii) (1 mark): Jack used 10.0 g of the mixture for his sample. He used a dish to weigh the pure salt he made. Mass of empty dish = 50.0 g Mass of dish with pure salt = 58.4 g
- June 2019, Chemistry Paper 2 Foundation, Q2(b)(iv) (2 marks): The percentage of pure salt in the mixture can be calculated using the formula: Percentage = mass of pure salt mass of mixture × 100 Calculate the percentage of
- June 2019, Combined Science Paper 4 Foundation, Q2(c) (3 marks): The pigments in red and blue tomatoes are water soluble. The students use paper chromatography to investigate the pigments in red and blue tomatoes. Complete th
- June 2019, Combined Science Paper 4 Foundation, Q2(d)(i) (3 marks): Calculate the Rf value of the red pigment in the red tomato extract, using Fig. 2.1. Use the formula: Rf = distance moved by red pigment in the red tomato extra
- June 2019, Combined Science Paper 4 Foundation, Q2(d)(ii) (2 marks): Explain why the line at the bottom of the chromatogram was drawn in pencil. [2]
- June 2019, Combined Science Paper 4 Foundation, Q2(d)(iii) (2 marks): Give two conclusions that the students can make from these results. Conclusion 1 Conclusion 2 [2]
- June 2019, Chemistry Paper 6 Higher, Q4(a) (2 marks): Why does this method work well in countries with warm climates? [2]
- June 2019, Chemistry Paper 6 Higher, Q4(b)(i) (4 marks): Jack collects a sample of solid salt. Describe an experiment that Jack could do to find out an accurate value for the mass of pure salt in his sample. [4]
- June 2019, Chemistry Paper 6 Higher, Q4(b)(ii) (3 marks): Here are the results of one experiment. Mass of salt mixed with sand = 5.42 g Mass of pure salt obtained = 1.36 g Calculate the percentage of pure salt in the s
- June 2019, Combined Science Paper 8 Higher, Q2(c) (3 marks): Outline the method to produce the chromatogram in Fig. 2.1. [3]
- June 2019, Combined Science Paper 8 Higher, Q2(d)(i) (2 marks): What do the results in Fig. 2.1 show? [2]
- June 2019, Combined Science Paper 8 Higher, Q2(d)(ii) (3 marks): Calculate the Rf of anthocyanin, using Fig. 2.1. Give your answer to 2 significant figures. Rf of anthocyanin = [3]
- June 2018, Chemistry Paper 2 Foundation, Q7(a) (2 marks): The tablets are a formulation and not a pure substance. Put ticks (✓) in one box in each row to show which statements about formulations and pure substances are
- June 2018, Chemistry Paper 6 Higher, Q6(a) (2 marks): The tablets are a formulation. What is the difference between a formulation and a pure substance? [2]
- June 2018, Chemistry Paper 6 Higher, Q6(b)(i) (1 mark): How can she tell that the dyes have not dissolved in the water? [1]
- June 2018, Chemistry Paper 6 Higher, Q6(b)(ii) (1 mark): What should she do to make a solution of the dyes? [1]
- June 2018, Chemistry Paper 6 Higher, Q6(c)(i) (2 marks): Use the scale given on the diagram to complete the table of results. Distance moved Distance moved by solvent (cm) by dye (cm) Red dye Yellow dye [2]
- June 2018, Chemistry Paper 6 Higher, Q6(c)(ii) (2 marks): Mia uses this formula to calculate the Rf value of each dye: distance moved by the dye Rf = distance moved by the solvent How could she use the Rf values of the
- June 2018, Chemistry Paper 6 Higher, Q6(c)(iii) (2 marks): Mia does a chromatography experiment for a green dye. This dye has an Rf value of 0.52. After the experiment the solvent front has travelled 8 cm from the start
- June 2018, Chemistry Paper 6 Higher, Q6(d) (1 mark): Explain why it was not necessary to use a locating agent in this experiment. [1]
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