Today’s Imponderable: How Does Salt Melt Ice?

Salt is one of the first things that most homeowners stock up on before a big blizzard hits. Even though you sprinkle salt on your driveway every year before and after a big snowstorm, do you really know what it is that causes salt to melt ice?

Salt lowers the freezing point of water, which is how it melts the ice on your walkway. Even though the ice isn’t technically water in a liquid state, it does have a thin layer of water at its surface, which is what enables the salt to do its job. The salt mixes with the water and melts the ice little by little, and then it changes its composition so that it now requires the temperature to drop significantly for it to refreeze. For areas with particularly cold temperatures, there are heavy-duty salts that require temperatures as low as -20 degrees in order for the ice to freeze again.

The next time you put on your warmest layers and trek out into the cold to salt your driveway, think about the complex chemical reaction that is about to happen. It just may make the grueling process a bit more fun!

Why Does Salt Melt Ice? []
Why do they use salt to melt ice on the road in the winter? [How Stuff Works]
How Salt Melts Ice [AccuWeather]

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