How freezing mixture works?

In our last article, we got to know how salt causes ice to melt. There is another phenomenon in which the addition of salt to water causes significant drops in the temperature. This phenomenon forms the basis of the freezing mixture.

Freezing mixtures are ordinary laboratory tools. They are used whenever you want to get to lower temperatures. They are also used for ice cream making at domestic level because these mixtures are so easy to make and they let you go down to -20degrees Celsius or so. So how do they work?

Well, its pretty simple. It is related to the phase change of solid ice. This is what comes in to play here. Actually, the salt that is added to water causes the ice to melt and ice needs some heat of fusion to be converted into the liquid state. It absorbs this energy from the surroundings and the temperature of the surrounding then falls well below the normal freezing point of water. This is how the overall system works. It is worth mentioning here that any salt can give the freezing mixture. Some common salts in the freezing mixtures are: 

Rock salt

Calcium Chloride

Magnesium Chloride

etc.