Question

What type of deviation is shown by ethanol and acetone mixture ? Give reason. What type of azeotropic mixture is formed by that deviation ?

Hint:

Positive deviation occurs when the interactions between molecules in the mixture are weaker than those in the pure components, leading to an increase in vapor pressure.

Answer 1

Ethanol and acetone mixture shows a positive deviation from Raoult's law. In this case, the intermolecular forces between ethanol and acetone molecules are weaker than the forces between ethanol molecules and between acetone molecules. This leads to an increase in vapor pressure of the mixture compared to what is predicted by Raoult's law for an ideal solution. This deviation leads to the formation of an azeotropic mixture. In this case, the azeotrope formed is a minimum boiling azeotrope, where the mixture boils at a lower temperature than either of the pure components. The azeotrope consists of approximately 89% ethanol and 11% acetone by mole.