The World Around Us

Chemicals in Our World

Why does salt melt ice?

Adding salt to ice lowers the melting point of water (see freezing-point depression in “Macroscopic Properties”). So when you pour salt on the ice on your driveway, the melting point of the saltwater mixture you made by adding the salt may be lowered sufficiently such that it is below the outside temperature, which means the solid ice will start to melt.


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