The effects of dissolved substances in boiling point and melting point are :-

1. On the boiling point of water. Some of the solute (salt) molecules occupy the surface, reducing the effective area for evaporation. Since evaporation is suppressed, the boiling point is raised. Salt water consequently boils at a temperature above 1000 C.

2. On the melting point of ice. This effect is known as that of a freezing mixture. If salt is mixed with ice, the melting point of ice is lowered. For example, salt is often sprinkled to melt snow. Salt is also added to ice while making ice cream by churning a pail in ice. Since the temperature drops, ice cream forms faster.