Solutions Question 304
Question: Which of the following liquid pairs shows a positive deviation from Raoult’s law-
Options:
A) Water - Nitric acid
B) Benzene - Methanol
C) Water-Hydrochloric acid
D) Acetone - Chloroform
Show Answer
Answer:
Correct Answer: B
Solution:
Positive deviations are shown by such solutions in which solvent-solvent and solute-solute interactions are stronger than becomes weaker. Therefore their escaping tendency increases which results in the increase in their partial vapour pressures. In pure methanol there exists intermolecular H-bonding. On adding benzene, its molecules come between methanol molecules there by breaking H-bonds which weaken intermolecular forces. This results in increase in vapour pressure.
