So it’s -10 °C where I am today and there are loads of puddles on the pavements and roads because they have been salted (I’m aware that the ground temperature might be higher than -10). But I can’t wrap my mind around the fact that above 0 °C salt can be solid but when it’s diluted into water it lowers the freezing temperature.
But to what temperature? Is there a point where salt is no longer effective on roads and pavements?
Does it depend on the amount of salt mixed with water?
When the sea freezes is it only the H2O that solidifies? What about the salt?
Please, this has kept me up at night!
In: Chemistry
Salt water has a freezing point below 0˚C. When you put salt on the ice, and then grind it with car tires, a little water is formed from the friction. This water dissolves some salt, and then the salt water wets the ice. At the boundary, the ice melts and makes more water which dissolves more salt which allows the salt water to spread over more ice, … .
The freezing point depends on the amount of salt in the water, from -3˚ for ocean water to -9.4˚ for water that’s saturated with table salt. You can get a little lower with specialized salts containing magnesium or potassium.
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