Question

What type of non – idealities are exhibited by cyclohexane – ethanol and acetone – chloroform mixture? Give reason for your answer.

Answer 1

Ideal solutions are those which obey Raoult’s law over extreme range of concentration.Ideal solutions have another important properties:

• ∆H_mix = 0 
• ∆V_mix = 0

Here-forces of attraction between A – A. B – B and A – B are of the same order. Non ideal solutions do not obey Raoult’s law over the entire range of concentration.

∆H_mixing ≠ 0 and ∆V_mixing ≠ 0.

Cyclohexane – ethanol mixture shows positive deviation from Raoult’s law because forces of attraction between cyclohexane and ethanol are less than in between pure cyclohexane as well as pure ethanol. 

Acetone-Chloroform mixture shows negative deviation from Raoults law because forces of attraction between acetone and chloroform are higher than that in between pure acetone and pure chloroform molecules.