A sample of potable water contains impurities - Edexcel - GCSE Chemistry - Question 9 - 2021 - Paper 1
Question 9
A sample of potable water contains impurities.
Why is this sample of water potable even though it contains impurities?
A. the impurities have no smell
B. the impur... show full transcript
Worked Solution & Example Answer:A sample of potable water contains impurities - Edexcel - GCSE Chemistry - Question 9 - 2021 - Paper 1
Step 1
Why is this sample of water potable even though it contains impurities?
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Answer
The correct answer is B. The impurities are colourless. This characteristic allows the water to be perceived as clean and safe for consumption, contributing to its classification as potable.
Step 2
What is sedimentation?
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Answer
The correct answer is C. The impurities in the waste water settle to the bottom of their container. This process allows for the removal of larger particles from the water, making it clearer.
Step 3
State why the waste water is filtered.
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Answer
The waste water is filtered to remove remaining impurities and particles that may not have settled during sedimentation. This ensures cleaner water that is safer for further treatment or discharge.
Step 4
State the reason for chlorination.
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Answer
Chlorination is performed to disinfect the water by killing harmful bacteria and pathogens. This step is critical to ensure that the water is safe for human consumption.
Step 5
Use the information about salt A and salt B in Figure 10 to evaluate this conclusion.
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Answer
From Figure 10, we observe that salt B consistently removes a higher percentage of impurities than salt A up to the addition of 200 mg. Additionally, the data suggests that adding 100 mg of salt B achieves optimal impurity removal. Thus, the conclusion that 100 mg of salt B is the best option for purifying waste water appears to be valid based on the experimental results.
Step 6
Devise a plan to separate pure water from this mixture, including a test to show that the water obtained is neutral.
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Answer
To separate pure water from the contaminated mixture, the following steps can be executed:
Filtration: Use filter paper in a funnel to separate solid impurities from the liquid. This will allow pure water to pass through while retaining the dissolved solid.
Evaporation: Heat the liquid collected from filtration to evaporate water, leaving behind any dissolved solids. Collect the vapor and condense it back into liquid water.
Testing for Neutrality: After collection, test the obtained water using pH paper or a pH indicator to ensure that it is neutral, indicating it is free from acidic or basic contaminants.
