GCSE Chemistry Required Practical: Purifying Water

Key Stage 4

Meaning

Analysis and purification of water from different sources.

Method

A sample of rain water, sea water and bottled 'spring' water should be supplied.

Testing the pH

1. Using a clean pipettes to add 2ml of a water sample to a test tube and label it.
2. Add 2 drops of pH Indicator to the test tube and record the colour and pH.
3. Repeat steps 1 and 2 for each water sample.

Finding Solutes

1. Measure the mass of a Watch Glass.
2. Add 4ml of a water sample to the watch glass.
3. Add 150ml of tap water to 250ml beaker.
4. Place the watch glass on top of the beaker.
5. Heat the water in the beaker to boiling and keep boiling until all the water in the watch glass has evaporated.
6. Allow the water to cool and then observe the watch glass for any remaining solutes.
7. Measure the mass of the Watch Glass with solutes and subtract the mass of the watch glass to find the mass of the solutes.
8. Repeat the experiment for each water sample using a clean watch glass each time.

Purifying Water

1. Add 40ml of a water sample to a 100ml conical flask.
2. Attach a bung and delivery tube to the top of the conical flask.
3. Place a Test Tube in a cold water bath.
4. Heat the water sample in the conical flask and arrange the delivery tube to pass the water vapour into the cold test tube where it will condense.
5. Use the water collected to repeat tests for pH and finding solutes.
6. Repeat 1-5 for each water sample.

References

AQA

Purification of water, pages 208-209, GCSE Chemistry; Third Edition, Oxford University Press, AQA