[poll id=”42″]
ANSWER: A – III<II<I
The solution that exhibits the highest freezing point is the one that has depressed the least.
I – CH3OH does not disassociate and thus its van’t hoff factor (i) is 1. (2m x 1) = 2
II – NaCl dissociates into 2 ions, Na+ and Cl- (i=2). (2m x 2) = 4
III – AlCl3 dissociates into 4 ions, 1 Al, and 3 Cl- (i=4). (2m x 4) = 8
CH3OH thus exhibits the smallest depression in freezing point, and thus has the higher boiling points. NaCl is 2nd, and AlCl3 is last, with the highest depression in freezing point.