On a snowy day, it’s no surprise that you’ll probably slip on ice. To solve this problem, people often put rock salt on the roads. Rather than unfreezing water, which would take hours to do, this simple solution is to go-to. So, how does this work?

Salt (chemically known as NaCI, or Sodium Chloride) consists of ions NA+ and CI-. Rock salt is applied to icy roads in the winter. This type of salt is the same as the salt you eat, except that rock salt has been crystallized into larger pieces. Normal salt is ground up and has a much smaller size than rock salt particles.

Salt causes a phenomenon called freezing point depression, meaning salt lowers the freezing point of water in cold temperatures. Normally, salt has a lower freezing point than compared to water. Since salt is soluble in water, salt sprinkled in water will dissolve when the salt ions react with water molecules. This reaction gives off heat; By dispersing a large amount of salt on roads, the dissolved salt lowers the freezing point of the water, causing the ice to melt and turn into water. When the concentration of salt is higher, the quicker the ice melts.