How does salt make icy roads safe?
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Salt lowers the freezing point of water. When you spread salt on a road, and cars drive on it, a bit of the ice melts from friction, and salt mixes with that water. That then helps melt more ice, which mixes with salt, until you have mostly salt water instead of ice on the roads.
Usually they don’t use regular salt, they use a mixture of different kinds of salt, like calcium chloride, and some sand, which helps cars get more traction on the ice.
Still, if it gets cold enough, salt doesn’t help much, because even salt water will freeze. In those cases, they usually mix in a lot more sand and tell people to stay off the roads.
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