Question

How can you obtain pure water from a salt-water mixture (or salt-solution) ? Draw a neat and labelled diagram of the apparatus you would use to obtain pure water from a salt-water mixture (or salt-solution).

Answer 1

We can obtain pure water from a saltwater mixture (or salt solution) by the process of distillation. Important steps underlying the process are as follows:

• The salt water mixture is taken in a distillation flask and heated subsequently.
• On heating, water vapours are formed that rise up and come through the side tube B.
• It is then passed through condenser C.
• Cold water from the tap is circulated in the outer tube of the condenser, so that the hot vapours are cooled.
• The vapours condense and are collected in another beaker.
• This pure water is called distilled water.
• Salt, being non-volatile, remains in the flask and can be obtained later.

Fig., separation of salt and water using distillation