Which water is which?
Learning Outcomes:
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To develop research skills.
To work in groups to solve a practical problem.
To plan a suitable experiment to gather sufficient data.
To revise practical skills from relevant science units.
Specification Links:
 OCR 21st Century Science C3 Unit – “Chemicals of the
environment”
 AQA Unit C3
You are provided with five samples of mineral water: A B C D and E
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One is water from Epsom.
One is Spring Water from Harrogate.
One is water from Sidmouth and is sea water
One is water from Shanklin on the Isle of Wight.
One is distilled water.
Your job is to identify and give reasons why you think you have
correctly identified those waters. You will need to think about what
experiments you need to do to carry out an accurate experiment
and how to make your results reliable.
You will also need to do some research into what dissolved salts
are present in each of the waters.
Equipment provided: Bunsens, matches, dry spills, damp spills,
beakers, evaporating basins, balances, pH indicator papers, UI
solution. You could ask for more!
A space for your ideas/research here:
Mineral water
A
B
C
D
E
Where is the mineral water from?
Give your reasons below saying why you think you are correct:
Teacher guide:
A = water with dissolved calcium sulphate
B = water with dissolved iron sulphate
C = water dissolved with sodium chloride
D = water (perhaps distilled)
E = magnesium sulphate
Possible approaches:
Students could measure pH of the solutions using UI or litmus paper.
Expected results:
Sample
Calcium sulphate
Iron sulphate
Sodium chloride
Distilled water
Magnesium sulphate
Results
Light blue (slightly alkaline)
Yellow (slightly acidic)
Green (neutral)
Green (neutral)
Light blue (slightly alkaline)
Students could evaporate each of the samples. Expected results:
Sample
Results
Calcium sulphate
Iron sulphate
Sodium chloride
Distilled water
Magnesium sulphate
White solid left
Yellow solid left
White solid left
No solid left
White solid left
Students could perform flame tests on the residual samples. Expected
results:
Sample
Calcium sulphate
Iron sulphate
Sodium chloride
Distilled water
Magnesium sulphate
Results
Orange-red
No obvious colour
Orange
n/a
No obvious colour
Students could find out the density of the solutions. This is not particularly
successful mainly because the balances are not accurate enough.