12.18. Give a brief description of the principles of the following techniques taking an example in each case.
This method is used for the purification of liquids from non-volatile impurities. It is based on the fact that fluids of having different boiling points vaporise at different temperatures. The impure liquid is boiled in a flask, and initially, the vapours of lower boiling points component are formed. The vapours are condensed by using a condenser, and the liquid is collected in a receiver. For example- Organic liquids such as benzene, toluene, xylene etc can be purified by this method.