ExamsMy practice
Ques. 1JEE Main 2024, 31 January (Morning Shift)
Identify the mixture that shows positive deviations from Raoult's Law
- (CH3)2CO + CS2
- (CH3)2CO + C6H5NH2
- CHCl3 + C6H6
- CHCl3 + (CH3)2CO
Answer
(1) (CH3)2CO + CS2
Solution
Positive deviation: A–B attractions weaker than A–A and B–B attractions ( mixH > 0).
(A): non-polar CS2 weakens the dipole–dipole attraction of acetone ⇒ positive deviation ✓
(B): H-bond between N–H of aniline and C=O of acetone ⇒ negative deviation
(C): C–H of CHCl3 attracted by the π-cloud of benzene ⇒ negative deviation
(D): H-bond Cl3C-H O=C(CH3)2 ⇒ negative deviation
Answer: (1)