The salt in life refers to the salt extracted from seawater, salt ponds, salt wells and salt mines. Its main component is sodium chloride (NaCl), which is called sea salt, pond salt, well salt and rock salt respectively. In the past and in the future, human beings depend on these salts to absorb the inorganic salts we need.
With the development of chemical industry and chemical science, the meaning of the word "salt" has been greatly expanded. Middle school chemistry textbooks say that "salt" refers to a compound composed of "metal ions" (including ammonium ions) and acid ions. They have many kinds, different properties, different appearances and different uses.
Because of the importance and high profits of salt, governments of past dynasties have adopted a monopoly policy on salt, so there is a difference between "official salt" and "private salt". In recent years, due to the requirements of nutrition and hygiene, a small amount of potassium iodide (KI) and other nutrients have been added in the process of processing raw salt into refined salt, so there are "qualified" and "unqualified" salts. The formulas of these salts are all differences in policy management, but there is no substantial difference in the composition of "salt". Without potassium iodide, there is no difference between "private salt" and "unqualified salt". Although it is illegal, it will not kill people, and there is no difference between "real salt" and "fake salt". Their main component is sodium chloride.
In the chemical industry, crude salt and processed salt are widely used as raw materials to produce chemical products such as chlorine, bleaching powder, caustic soda and soda ash, which are mainly composed of chlorine and sodium. Edible salt and industrial salt have the same chemical composition, but their uses are different. Because crude salt is a natural product, refined salt is also obtained by simple processing of crude salt. Besides the main components of sodium chloride, it also contains many impurities, so it can't be called sodium chloride. Instead, it is customary to use only one word "salt" to refer to those with sodium chloride as the main component, such as crude salt, sea salt, well salt, rock salt, iodized salt, non-iodized salt, refined salt, big salt, broken salt and washed salt. If it is a salt containing other chemical components, be sure to specify its specific trade name or chemical name, such as soda ash, baking soda, alum, ammonium sulfate, potassium nitrate, potassium chloride, diammonium hydrogen phosphate, etc. And never call it "industrial salt" in general.