Question

One mole of two different compounds happens to weight the same, but one compound ionizes in water and the other does not. Which will give the lowest freezing point depression?

Answer 1

The species that ionizes will give the GREATER freezing point depression.

Explanation:

A binary ionic species, `MX`, will give rise to two species in solution, i.e:

`MX(s) rarr M^(+)(aq) + X^(-)(aq)`

The ions are aquated by several water molecules, and are hence represented as `M^(+)(aq)`. And since `"freezing point depression"` is a colligative property that depends on the number of particles in solution, the binary salt will give TWICE the freezing point depression of a neutral solvate.