Which substance will most affect the freezing point of water if 1 mole of the substance is added to 1 kilogram of water? A.) LiF B.) Ca(NO3)2 C.) Mg3N2 D.) C6H12O6

Answer 1

The depression of the freezing point is a colligative property, and as such, it depends on the total number of particles in solution. For this problem, we want to look for the substance that will produce the greatest number of particles upon dissociation.

A) LiF = 1Li⁺ + 1F^- ions = 2 particles

B) Ca(NO3)2 = 1Ca²⁺ + 2 NO3^- ions = 3 particles

C) Mg3N2 = 3Mg²⁺ + 2N^3- ions = 5 particles

D) C6H12O6 = C6H12O6 = 1 particle

Since all are present at 1 molal, the greatest effect on freezing point will be (C) Mg3N2