Here's why:

* Freezing Point Depression: Antifreeze (typically ethylene glycol or propylene glycol) is a solute that disrupts the formation of ice crystals in water. This disruption lowers the temperature at which the water will freeze.

* Colligative Property: Freezing point depression is a colligative property, meaning it depends on the concentration of the solute (antifreeze) in the solvent (water), not on the specific type of solute.

So, adding antifreeze to water doesn't freeze the antifreeze itself, but rather prevents the water from freezing at temperatures below its normal freezing point of 0°C (32°F).