WHY DOES SALT MELT ICE?
When snow is on the horizon, you might have noticed large lorries spreading rock salt on the roads and pavements to prevent them getting slippery. But how does salt get rid of ice?
Icy roads tend to have a thin layer of water covering the ice. This liquid water melts the ice, while the ice simultaneously freezes the water. This balances out so that the amount of water and ice remains constant. But not once you add salt.
Salt is made up of positive sodium and negative chloride ions. These charged particles dissolve in water, disrupting the arrangement of water molecules and making it more difficult for structured ice crystals to form. This lowers the freezing point of water, meaning colder temperatures are required for ice to form. The ice on the ground can no longer freeze the water at zero degrees Celsius. However, the water can still melt the ice. Ultimately, this leads to less ice on the roads.