The science of salting roads: How city streets are being kept safe

The science of salting roads: How city streets are being kept safe Road salt is a cheap and effective way of keeping city streets safe from ice Salt is able to melt ice due to the scientific principle of freezing point depression The salt impedes the ability of the water molecules to form solid ice crystals Road salt can hurt the environment, so other alternatives are being considered

By Julie Pollock For The Conversation

Published: 17:28 GMT, 1 February 2019 | Updated: 05:47 GMT, 2 February 2019

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Brrr…it’s cold out there! Children are flocking to the television in hopes of hearing there will be a snow day; the bread and milk aisles at grocery stores are empty because of an impending snow storm; and utility trucks are out spraying salt or salt water on the roads. 

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?

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The rock salt from salt trucks is very similar to the salt you have on your dinner table – it’s the same sodium chloride, NaCl, except it has a brownish gray color due to mineral contamination

The rock salt from salt trucks is very similar to the salt you have on your dinner table – it’s the same sodium chloride, NaCl, except it has a brownish gray color due to mineral contamination

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.  

Road salt is a cheap and effective way to protect roads from ice due to a simple scientific principle: freezing point depression of solutions. The salt prevents the water molecules from . The degree of freezing point depression depends on how salty the solution is.

Road salt is a cheap and effective way to protect roads from ice due to a simple scientific principle: freezing point depression of solutions. The salt prevents the water molecules from forming ice crystals . The degree of freezing point depression depends on how salty it is

Road salt can be damaging to the environment, so research groups have developed alternatives, by looking into additives such as beet juice (pictured)

Road salt can be damaging to the environment, so research groups have developed alternatives, by looking into additives such as beet juice (pictured)

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 F or

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