Question

How can we purify tap water? Explain.

Answer 1

Tap water - It is freshwater or potable water that is used for human consumption and contains dissolved salts and gases.

Why does tap water need to be purified?

1. It contains dissolved salts.
2. It contains dissolved gases.
3. It is not suitable for use in chemical reactions and solution preparation in industries.
4. It can be purified by the process of distillation.

Distillation – the process by which a soluble liquid can be separated from a solution by first converting it into vapours by evaporation and then cooling and collecting the vapours by condensation in another container is called distillation.

Process of distillation of tap water:

Step 1 - Setting up the assembly:

1. Take a round bottom flask and add tap water into it, now put a thermometer into it to check the temperature.
2. Connect the flask with a condenser with a continuous flow of cold water from one end.
3. Attach another clean flask at the end of the condenser to collect the distilled water.

Step 2 - Evaporation:

1. heat the water slowly but do not boil the water.
2. Now the water will be converted into water vapour that will rise above and go through the condenser.

Step 3 - Condensation:

1. The water vapour coming from the flask will be cooled when it comes in contact with the walls of the condenser.
2. The cooled vapour will be again converted into liquid water that will flow down the condenser to another flask.

The water finally obtained in another flask is free from any dissolved salts and impurities and is called distilled water.