1, normal salt: composed of metal ions (including ammonium ions) and nonmetallic ions.

2. Acid salt: It consists of metal ions (including ammonium ions), hydrogen ions and nonmetallic ions.

3. Basic salt: It consists of metal ions (including ammonium ions), hydroxide ions and nonmetallic ions.

Chemically, salts in a broad sense are neutral (uncharged) ionic compounds composed of cations (positively charged ions) and anions (negatively charged ions). Such as calcium sulfate, copper chloride and sodium acetate. Generally speaking, salt is the product of double decomposition reaction, such as sulfuric acid and sodium hydroxide to produce sodium sulfate and water, and other reactions can also produce salt, such as displacement reaction.

Usually, under standard conditions, insoluble salts will be solid, but there are exceptions, such as molten salts and ionic liquids. Soluble salt solution and molten salt are conductive, so they can be used as electrolytes. There are many different salts in cytoplasm, blood, urine and mineral water.

The role of salt:

1, help digestion: the salty taste of salt can stimulate people's taste and increase oral saliva secretion, thus stimulating appetite and improving food digestibility.

2. Participate in body fluid metabolism: Salt is an important component of body fluid and participates in body fluid metabolism after intake. Therefore, people who sweat too much at work in high temperature need to supplement salty drinks.

3, anti-inflammatory swelling: salt has the effect of sterilization and anti-inflammatory, but also has the effect of coagulation and help stop bleeding.