The freezing point of a mixture of water and salt is lower than the freezing point of pure water.

Here's why:

* Freezing Point Depression: Adding salt to water disrupts the formation of the regular ice crystal structure. The salt ions (sodium and chloride) get in the way of the water molecules bonding together into a solid.

* Colligative Property: Freezing point depression is a colligative property, meaning it depends on the number of solute particles (in this case, salt ions) dissolved in the solvent (water), not the specific type of solute. The more salt you add, the lower the freezing point.

This is why salt is used to melt ice on roads in winter. The salt lowers the freezing point of the ice, causing it to melt even when the air temperature is below 0°C (32°F).