AQA GCSE Chemistry (8462), Higher tier · Atomic structure and the periodic table › Atoms, isotopes and electronic structure
Practise Mixtures. 14 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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This question is about mixtures and how they are separated. What is a mixture?
Two or more elements or compounds that are not chemically combined.
A student heated blue copper(II) sulfate solution in a flask. The flask was connected to a water-cooled condenser. A thermometer was placed at the top of the flask, level with the side arm that led to the condenser. A liquid was collected in a beaker at the end of the condenser. Name this separation technique.
simple distillation
Suggest a mixture from which a solid could be obtained by heating the mixture in an evaporating basin.
e.g. salt solution (salt dissolved in water)
Name the method that should be used to separate ethanol from mixture 1.
fractional distillation
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
This question is about mixtures and how they are separated.
(a) Which method would separate sand from a mixture of sand and water? Tick (✓) one box.[1]
Chromatography
Crystallisation
Filtration
Fractional distillation
(b) Which method would separate the different coloured dyes in a sample of ink? Tick (✓) one box.[1]
Chromatography
Crystallisation
Filtration
Fractional distillation
(c) What is a mixture?[2]
(d) Separating a mixture does not make any new substances. What type of process is used to separate a mixture?[1]
Show the answer and mark scheme
(a)Answer: Filtration
(b)Answer: Chromatography
(c)Answer: Two or more elements or compounds that are not chemically combined.
two or more elements or compounds / substances
not chemically combined (together)
(d)Answer: a physical process
physical (process)
Question 2Medium6 marks
A student heated blue copper(II) sulfate solution in a flask. The flask was connected to a water-cooled condenser. A thermometer was placed at the top of the flask, level with the side arm that led to the condenser. A liquid was collected in a beaker at the end of the condenser.
(a) Name this separation technique.[1]
(b) Describe what happens to the water in the flask and in the condenser.[2]
(c) The thermometer read 100 °C while the liquid was being collected. What does this show about the liquid collected?[1]
(d) What colour is the liquid collected in the beaker? Give a reason for your answer.[2]
Show the answer and mark scheme
(a)Answer: simple distillation
(simple) distillation
(b)Answer: The water boils/evaporates in the flask; the water vapour is cooled and condenses in the condenser.
water evaporates / boils (in the flask)
(water vapour / steam) is cooled and condenses (in the condenser)
(c)Answer: It is (pure) water, because water boils at 100 °C.
it is (pure) water / 100 °C is the boiling point of water
(d)Answer: Colourless; the copper(II) sulfate does not evaporate, so it stays in the flask.
colourless
copper(II) sulfate does not evaporate / boil (at 100 °C) so it stays in the flask
Question 3Hard6 marks
A technician has a sample of copper(II) sulfate solution that is contaminated with powdered carbon. Carbon is insoluble in water.
Plan a method the technician could use to obtain both pure water and crystals of copper(II) sulfate from the contaminated solution. You should name the apparatus used in each stage.[6]
Show the answer and mark scheme
Answer: Filter out the carbon; distil the filtrate to collect pure water; stop before the solution is dry, then crystallise the concentrated solution and filter and dry the crystals.
filter the mixture using filter paper in a funnel
carbon is left as the residue; copper(II) sulfate solution passes through as the filtrate
heat the filtrate in a flask connected to a water-cooled condenser (simple distillation)
water boils / evaporates and the vapour cools and condenses in the condenser; collect the pure water in a beaker
a thermometer at the side arm reading 100 °C shows the distillate is water
stop heating before the flask is dry, when the solution is concentrated / crystals start to form
pour the hot concentrated solution into an evaporating basin and leave it to cool so that crystals form
filter off the crystals and dry them between filter papers / in a warm oven
Marked with levels of response: the full level descriptors are in the app.