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Water from reservoirs is treated and tested before it is supplied to our homes - Edexcel - GCSE Chemistry - Question 1 - 2016 - Paper 1
Question 1
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Water from reservoirs is treated and tested before it is supplied to our homes.
(a) Give a reason why water is tested before it is supplied to our homes.
(b... show full transcript
Worked Solution & Example Answer:1
Water from reservoirs is treated and tested before it is supplied to our homes - Edexcel - GCSE Chemistry - Question 1 - 2016 - Paper 1
Step 1
Give a reason why water is tested before it is supplied to our homes.
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Answer
Water is tested to check for purity, ensuring there are no harmful substances or bacteria, making it safe for consumption.
Step 2
Explain how you could show which sample was hard water and which sample was soft water.
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Answer
To distinguish between hard and soft water, you would use soap. When hard water is mixed with soap, it forms a scum, indicating it does not lather well. In contrast, soft water will produce a lather without forming scum.
Step 3
Which of these ions causes hardness in water?
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Answer
B magnesium ions
Step 4
Describe a test to show whether the hardness in a sample of water is temporary or permanent.
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Answer
One could boil a water sample. Temporary hardness will resolve after boiling, causing any precipitate to disappear. In contrast, permanent hardness remains unchanged after boiling.
Step 5
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
To calculate the concentration, use the formula: concentration = mass (g) / volume (dm³). Here: concentration = 1.0 g / 1.0 dm³ = 1.0 g dm⁻³. Therefore, the answer is C 1.0.
