Why does salt sprinkled on icy roads cause the ice to melt?


Quick Answer

Salt is strewn on roads in winter in order to lower the freezing point of water, which has the effect of preventing new ice from forming. While salt does not directly melt ice, any ice that does melt is prevented from refreezing, effectively reducing the amount of ice present.

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Full Answer

Ice is pure water and a solid, meaning that salt is unable to dissolve into the ice below its melting point. Since freezing point depression works based on having a dissolved substance in the water, any substance that dissolves in water would be just as effective as salt. Salt is used because it is significantly cheaper and more abundant that other alternative substances.

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