All topics › AQA GCSE Chemistry › Potable water10.1.2 Potable waterAQA GCSE Chemistry (8462), Higher tier · Using resources › Earth's resources and potable water
Practise Potable water. 19 exam-style questions plus unlimited generated ones 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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Name the process used to remove dissolved salts from sea water to make it potable. desalination
Give two ways the student could measure the pH of each sample. Universal indicator (with a colour chart); a pH probe (pH meter). Sample questions Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1 Easy 4 marks
(a) What is potable water?[1]
(b) Which substance is used to sterilise drinking water?one box.[1]
Carbon dioxide Chlorine Nitrogen Sodium chloride (c) Give one other method used to sterilise drinking water.[1]
(d) Explain why potable water is not pure water in the chemical sense.[1]
Show the answer and mark scheme (a) water that is safe to drink (b) Answer: Chlorine
(c) ozone / ultraviolet (UV) light (d) it contains dissolved substances (e.g. salts) Question 2 Medium 6 marks
In the UK, rain provides water with low levels of dissolved substances. This fresh water collects in the ground and in lakes and rivers.
(a) Describe how potable water is produced from fresh water in the UK.[4]
(b) Explain why the amount of chlorine added to drinking water must be carefully controlled.[2]
Show the answer and mark scheme (a) choose an appropriate source of fresh water (e.g. ground water, a lake or a river) because it has low levels of dissolved substances / salts pass the water through filter beds to remove (insoluble) solids / particles sterilise the water with chlorine / ozone / ultraviolet light to kill microbes / bacteria (b) too little chlorine would not kill all the microbes too much chlorine is harmful / toxic / gives the water an unpleasant taste Question 3 Hard 6 marks
Potable water can be produced from ground water in the UK and from sea water in some hot, dry countries.
Compare how potable water is produced from ground water in the UK with how it is produced from sea water.[6]
Show the answer and mark scheme ground water is fresh water (from rain) with low levels of dissolved substances an appropriate source of fresh water is chosen the water is passed through filter beds to remove solids the water is sterilised with chlorine, ozone or ultraviolet light to kill microbes sea water contains high levels of dissolved salts, which must be removed (desalination) desalination by distillation (boiling the water and condensing the steam) or by reverse osmosis (using membranes) desalination requires large amounts of energy, so it is expensive and only used where fresh water supplies are limited water from both sources must be safe to drink: low levels of dissolved salts and microbes Marked with levels of response: the full level descriptors are in the app.
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