# Does freezing a substance change it?

Oct 24, 2017

Freezing is a physical change. It involves a liquid changing states to a solid.

Thus, freezing a substance will not change its chemical identity, but its state.

Nov 5, 2017

Freezing a substance is definitely a physical change, but the act of freezing it can have varied results depending on the substance and the temperature.

#### Explanation:

For example, when liquid water reaches about ${4}^{0} C$, the liquid achieves its maximum density, at which point the water starts to form ice crystals. Then the change in density of the altered liquid reverses and starts to expand until the ice reaches a lower density at ${0}^{0} C$. As a result, ice floats, which is hugely important to life on earth.

If you are freezing a substance that is already a solid, it will usually become more brittle as the temperature is reduced, and so will break easier. Consider an orange, or a length of aluminum extrusion, that can be shattered easily after being dipped into liquid nitrogen.

As the temperature of a substance is further reduced, scientists have observed many strange and interesting physical changes taking place, particularly when the temperature is reduced to near absolute zero or ${0}^{0} K$ or $- {273}^{0} C$.