Rock salt and table salt (also known as refined salt or common salt) are both sodium chloride (NaCl) compounds, but they have different forms and degrees of purity. Rock salt is typically found in nature as large mineral crystals, while table salt is a refined, processed form of salt that is commonly used for cooking and seasoning.
When you place rock salt inside a freezer at home, it does not transform into table salt. The rock salt will remain rock salt even in the freezer, as long as it doesn't undergo any chemical reactions or processes. The temperature of a typical home freezer is not sufficient to cause any significant changes in the composition or structure of the rock salt.
However, if you are using rock salt to create a saltwater-ice mixture for making homemade ice cream or chilling beverages, the freezing process might dissolve some of the salt in the water, creating a saltwater solution. In this case, the salt in the solution will remain as sodium chloride, but it will be dispersed throughout the liquid, not in its original crystal form.
To obtain table salt from rock salt, an industrial process known as salt refining or purification is used. This process involves crushing the rock salt into small grains or powder, followed by purification steps to remove impurities and minerals, leaving behind almost pure sodium chloride. Additional processes, such as iodization or the addition of anti-caking agents, might be employed to produce the table salt commonly used in households.
It's important to note that rock salt and table salt have different purposes. Rock salt is often used for de-icing roads, while table salt is used for cooking, seasoning, and food preservation. Table salt is more suitable for culinary purposes due to its fine texture and purity, while rock salt's larger crystals are preferred for certain applications, such as in salt grinders or for curing meat.