Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Separation of mixtures
19 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
2 marks · Normal
Answer and see the solution →State one separation technique that could be used to obtain pure water from salty water, and one technique that could be used to obtain pure salt from salty water.
Question 2
4 marks · Normal
Answer and see the solution →(a)[2 marks]Describe the steps needed to obtain pure crystals of copper sulfate from a mixture of copper sulfate and sand.
(b)[2 marks]Explain why filtration is a necessary step in this process.
Question 3
3 marks · Normal
Answer and see the solution →Explain why fractional distillation is able to separate ethanol from water, but simple distillation cannot produce pure ethanol from the mixture.
Question 4
4 marks · Normal
Answer and see the solution →The table shows the boiling points of four different substances found in a mixture. Substance Boiling point (°C) Propane -42 Methanol 65 Ethanol 78 Water 100 (a)[1 mark]State which substance would be collected first if the mixture is separated by fractional distillation.
(b)[1 mark]Explain why.
(c)[1 mark]Two of the substances have boiling points within 13°C of each other. Identify them.
(d)[1 mark]Suggest which technique should be used to separate the solid impurities from this mixture before distillation.
Question 5
1 mark · Normal
Answer and check →Which of the following is the correct definition of the residue in filtration?
- A.The liquid that passes through the filter paper
- B.The solid left behind on the filter paper
- C.The mixture before filtration begins
- D.The solution obtained after crystallisation
Question 6
2 marks · Normal
Answer and see the solution →Give two reasons why chromatography is useful for separating the components of ink.
Question 7
4 marks · Normal
Answer and see the solution →(a)[3 marks]A student wants to separate a mixture of ethanol, water, and some insoluble sand. Describe the sequence of separation techniques they should use to obtain pure ethanol.
(b)[1 mark]Explain why each technique is used at each stage.
Question 8
3 marks · Normal
Answer and see the solution →A student has a mixture containing 20.0 g of potassium nitrate (which is soluble in water) and 8.0 g of sand (which is insoluble in water).
She adds 100 cm³ of water and stirs the mixture, dissolving all of the potassium nitrate but none of the sand.
She filters the mixture to separate the sand from the solution and then uses crystallisation to obtain solid potassium nitrate from the filtrate.
Calculate the mass of residue and filtrate obtained after filtration. State which substances are present in each.