What is a fractionating column? Give its importance in fractional distillation.

Fractionating column : Fractionating columns help to separate the mixture by allowing the mixed vapors to cool, condense, and vaporize again in accordance with Raoult's law. ... In a typical fractional distillation, a liquid mixture is heated in the distilling flask, and the resulting vapor rises up the fractionating column

Importance :

The column in a fractionating column holds the material used in the fractionation process that creates the fractionation and causes the separation between two components with different boiling points. If you don’t have some kind of packing material, plates or trays or even indentations that are used in a Vigreux column you have no ability to separate the mixture.

The fractionating column itself contains the means to separate the lower-boiling material from the higher-boiling material. The column contains some kind of packing that provides pathways for the uprising vapors to contact downflowing liquid.  

The type of packing material or column construction determine the degree of separability that you can obtain. The more channels you can create (in other words the finer the packing and the more vapor-liquid contact you can create) the better separation you can achieve.

Explanation: