An ___ can be defined as a non-ideal solution whose vapour composition is same as its liquid.
Let’s take simple example to explain Azeotrope.
Nitric acid has 83∘C as boiling point and water has 100∘C as boiling point. When 68% of nitric acid & 32% of water is mixed and made a solution, the boiling point of the solution is 125.5∘C.
Normal ideal solutions which have different components with different boiling points can be easily separated by boiling the solution, the component with less boiling point changes to vapour first leaving the high boiling point liquid in the container.
This process is what we call fractional distillation.
Where as in azeotropic mixture, solution has different boiling point compared to boiling points of components and solutions boils only above this temperature & both components change to vapour phase together and maintains the composition same as in liquid phase.
So it is impossible to separate them by fractional distillation.