What is the role of fractionating column in fractional distillation ?Why can`t fractional distillation occur without a fractionating column ?What is the role of thermometer in distillation ?

Dear student!

The fractionating column, is used to separate the liquids according to the order of their vaporization, so that they get separated as they are vaporized.

The distillation process with fractional column is called the fractional distillation and it is an special type of distillation in which two miscible liquids having different boiling points but closed to each other are separated by fractionating column. 

The thermometer is used to detect the temperature change and balance in the system.