A sample of potable water contains impurities - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2021 - Paper 1
Question 6
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 impu... show full transcript
Worked Solution & Example Answer:A sample of potable water contains impurities - Edexcel - GCSE Chemistry Combined Science - Question 6 - 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 C. the impurities are harmless. Even though the water contains impurities, if they are harmless, it can be deemed safe for consumption.
Step 2
What is sedimentation?
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Answer
C. the impurities in the waste water settle to the bottom of their container. This process allows solid particles to separate from the liquid, making the water clearer.
Step 3
State why the waste water is filtered.
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Answer
The waste water is filtered to remove any remaining solid particles and impurities that may not have settled during the sedimentation process, ensuring cleaner water for further treatment.
Step 4
State the reason for chlorination.
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Answer
Chlorination is carried out to kill harmful microorganisms and pathogens in the water, making it safe for drinking.
Step 5
Use the information about salt A and salt B in Figure 7 to evaluate this conclusion.
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Answer
The addition of 100 mg of salt B effectively removed a higher percentage of impurities compared to salt A across various concentrations. Thus, it is reasonable to conclude that salt B is more efficient for purifying waste water, as demonstrated by the experimental data represented in Figure 7.
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 mixture, follow these steps:
Filtration: Use filter paper to separate the solid contaminants from the liquid.
Evaporation: Heat the filtrate in an evaporating dish to boil off the water, leaving behind any dissolved solids.
Condensation: Collect the vapor using a condenser, allowing it to cool and return to liquid form.
Test for Neutrality: To test if the water is neutral, use pH paper or a pH meter. The water should register a pH of around 7 to confirm it is neutral.
