The salt has expired for three years and cannot be eaten.

Usually you cannot eat salt after it has expired. Harmful substances are likely to appear after the expiration date. Table salt has a certain shelf life. If it exceeds the shelf life, it is likely to cause the loss of nutrients in the salt. At the same time, if the salt is stored incorrectly, such as when the salt is damp or contaminated, it is likely to produce many harmful substances. .

In addition, most table salt is iodized salt. Iodine is very important to the body. Eating expired table salt may cause insufficient iodine intake. It is recommended that when eating salt, it must be within the shelf life, and you should also pay attention to a low-salt diet. Table salt, in terms of classification, includes well salt, sea salt, pool salt, rock salt, etc.

Chemical properties of salt

NaCl, the main component of table salt, is an ionic compound. Pure sodium chloride crystals are colorless and transparent cubic crystals. Due to the presence of impurities, sodium chloride is generally white cubic crystals or fine crystal powders with a specific gravity of 2.165 (25/4°C) and a melting point of 801°C. The boiling point is 1442°C, the density is 2.165g/cm2, it tastes salty, and it easily deliquesces when it contains impurities.

Soluble in water or glycerol, insoluble in ethanol, insoluble in hydrochloric acid, the aqueous solution is neutral and conductive. Solid sodium chloride does not conduct electricity, but molten sodium chloride conducts electricity. Solubility in water increases slightly with increasing temperature.

The above content refers to Baidu Encyclopedia-Salt