Kate's Corner: Why salt melts ice

By  | 

BRIDGEPORT, W. Va. (WDTV) - Even though lately it has been feeling more like spring as opposed to winter, wintry roads are always on our mind. One major tool when it comes to combating icy roads is salt. How can it be that something that isn't hot is melting the ice?

Well first let's talk about how water becomes ice. Pure water freezes at 32 degrees Fahrenheit or zero degree Celsius. When the temperature drops, free flowing molecules organize into crystal structures and ice is formed. Salt works to disrupt that process.

When the salt hits the ice, it breaks up into two ions: Sodium and Chloride. These ions move around and push the water's molecules apart. This process is called "Freezing Point Depression." In more simple terms, salt lowers the freezing point of water.

However, salt isn't unstoppable. It can only act as a deicer at temperatures above 16 degrees Fahrenheit or negative 9 degrees Celsius.

20 million tons of road salt is used annually here in the U.S. However salt is can be expensive so a cheaper abrasive alternative is sand. Sand also doesn't have as many potentially negative effects on the environment as salt does.

Now you'll know the science behind the truck laying down salt next time you see them out of the roads.