Salt water doesn't freeze at a single, fixed temperature like pure water does. The freezing point of saltwater depends on the concentration of salt dissolved in it.

Here's why:

* Salt disrupts the formation of ice crystals: When pure water freezes, water molecules form a regular crystalline structure. Salt ions (sodium and chloride) interfere with this process, making it harder for the water molecules to arrange themselves into ice.

* Higher salt concentration = lower freezing point: The more salt dissolved, the more the freezing point is lowered.

General Guidelines:

* Ocean water: With an average salinity of around 3.5%, ocean water freezes at about -1.9°C (28.6°F).

* Higher salt concentrations: For saltier solutions, like brine used in ice cream making, the freezing point can be significantly lower.

Important Note: It's essential to understand that the freezing point depression is not linear. The relationship between salt concentration and freezing point isn't straightforward and requires specific calculations for precise values.