Edible salt refers to the processed edible salt with sodium chloride as the main component obtained from seawater, underground rock (mineral) salt deposits and natural brine (salty) water, excluding low sodium salt. The main component of edible salt is sodium chloride (NaCl), and it also contains a small amount of water, impurities, iron, phosphorus, iodine and other elements.
Salt is a colorless and transparent cubic crystal with a melting point of 80 1℃, a boiling point of 14 13℃ and a relative density of 2. 165. When containing impurities, it is salty and easy to deliquesce; Soluble in water or glycerol, slightly soluble in ethanol, insoluble in concentrated hydrochloric acid, the aqueous solution is neutral. With the increase of temperature, the solubility in water increased slightly. When the temperature is lower than 0. 15℃, NaCl dihydrate can be obtained.
Sodium chloride is abundant in seawater and natural salt lakes, and can be used to produce chlorine, hydrogen, hydrochloric acid, sodium hydroxide, chlorate, hypochlorite, bleaching powder and metallic sodium. It is an important chemical raw material. It can be used for seasoning food and curing fish and vegetables, as well as salting out soap and tanning leather. Highly refined sodium chloride can be made into physiological saline for clinical treatment and physiological experiments, such as sodium loss, water loss and blood loss. Sodium chloride can be prepared by concentrating crystallized seawater or natural salt lake or salt well water.
Edible salt is iodized salt made by adding a certain amount of iodine agent into refined salt, broken washing salt and sun-dried salt. Iodine in salt can only exert its biological activity in human body after it is converted into iodine ion. Iodide is very unstable in nature, and it is easy to decompose and volatilize and fail.