Question

explain two methods of distillation(25marks) tq

in advance

explain two method of distillation of brown spirit

Answer 1

Types of Distillation

SIMPLE DISTILLATION

If water is stored in a sealed container and allowed to evaporate, there will be a point where it will reach equilibrium such that the water vapour is condensing just as fast as the water is evaporating. The pressure of the vapour at this equilibrium point is called ‘vapour pressure’. Vapour pressure is different for different substances as well as different for different temperatures. If a mixture consists of two different liquids with different boiling points, the vapour will contain more of the liquid that is volatile, i.e., which evaporates faster. In simple distillation, the mixture is heated making the vapour rise through a tube, which is then collected and recondensed. The recondensed liquid will have a greater concentration of the volatile liquid rather than the original mix. If two liquids in the original mixture have widely different boiling points, a one-step evaporation and recondensation process is all the is required. This process is termed as Simple Distillation.

FRACTIONAL DISTILLATION

Fractional Distillation is a method that is used to separate a mixture of liquids that have similar boiling points. It involves several vaporization-condensation steps which are conducted in a fractioning column. This process is also termed as rectification. On heating, the liquid mixture is converted into vapours that rise into the fractioning column. On cooling, the vapours condense on the walls of the condenser. The hot vapours coming out from the distilling flask now heat the condensed vapour, thereby creating new vapours. Many such cycles take place, thereby ensuring that the purity of the distillate improves with every cycle.