Question

The boiling point of an azeotropic mixture of water and ethyl alcohol is less than that of theoretical value of water and alcohol mixture. Hence, the mixture shows :

• A. that solution is highly saturated
• B. positive deviation from Raoult's law
• C. negative deviation from Raoult's law
• D. nothing can be said

Answer 1

The correct option is B positive deviation from Raoult's law

Option (B) is correct. The mixture shows positive deviations from Raoult's law.
Positive deviations from Raoult's law are noticed when
(i) Exp. value of vapour pressure of mixture is more than calculated value.
(ii) Exp. value of b.pt. of mixture is less than calculated value.
(iii) ${\Delta }_{mixing}=+ve$
(iv) $\Delta V_{mixing}=+ve$