Expert: George Maxwell - 11/13/2007

Question
does salt or sugar water freeze at a different time than regular water?

Answer
Hi, and thanks for your question.

Pure water at atmospheric pressure always freezes at O degree centigrade. If you add salt, sugar or any other substance that dissolves in water, the freezing point is lowered.

The freezing point of a water-based solution is always lower than the freezing point of pure water.
Adding more salt / sugar /etc increases the concentration of the solution you form, and so the freezing point gets lower as you add more substance.

It's important to note that this rule only applies for substances that dissolve in water. For instance, if you put sand in water, the sand sinks to the bottom and doesn't dissolve, so the freezing pont of the water remains unchanged.

Note that water itself is a chemical (a compound of hydrogen and oxygen).

Hope this helps!