Here's why:

* Freezing Point Depression: The addition of a solute (like salt) to a solvent (like water) lowers the freezing point of the solvent. This is known as freezing point depression.

* Disruption of Water Molecules: Salt dissolves in water, creating ions (sodium and chloride ions in this case). These ions disrupt the normal hydrogen bonding between water molecules, making it harder for the water molecules to form the regular, crystalline structure of ice.

* Lower Energy Required: As a result, a lower temperature is required to freeze the water. Conversely, the ice will melt at a lower temperature than pure ice.

Practical Example: This is why salt is used to melt ice on roads in winter. The salt lowers the freezing point of the water, making it melt even at temperatures below 0°C (32°F).