Question

How do dissociation of solute molecules affect a colligative property?

Answer 1

1. Dissociation of solute molecules increases the number of solute particles in a solution because each molecule splits into two or more ions.
2. Since colligative properties (like boiling point elevation, freezing point depression, osmotic pressure, and vapour pressure lowering) depend only on how many solute particles there are, this increase causes a bigger effect on the colligative property than we would normally expect.
3. As a result, the observed colligative property becomes stronger, and the calculated molecular mass appears lower than the actual value.
4. In such cases, the van’t Hoff factor (i) is greater than 1, reflecting the increase in particle number due to dissociation