How winter salt actually works
With the occasional assist from beet juice and molasses.
We all know why the first two happen—kids are excited for a day off of school filled with hot chocolate and snowmen. Adults are stocking up on necessities. But what’s up with those trucks?
They’re working to protect drivers from slippery conditions by spraying rock salt or a solution of salt water to prevent ice formation. This salt is very similar to the salt you have on your dinner table—it’s the same sodium chloride, NaCl. There are some proprietary mixtures that contain other salts—such as potassium chloride (KCl) and magnesium chloride (MgCl) – but they’re not as commonly used.
Road salt isn’t as pure as what you use on your food; it has a brownish gray color, mostly due to mineral contamination. Subjecting the environment to this salt via runoff can have some unintended consequences including negative effects on plants, aquatic animals and wetlands.
But it’s a cheap and effective way to protect roads from ice due to a simple scientific principle: freezing point depression of solutions. The freezing point of pure water, the temperature at which it becomes ice, is 32 degrees Fahrenheit. So if there’s snow, sleet, or freezing rain and the ground is 32 degrees or colder, solid ice will form on streets and sidewalks.
Read the full article here.