In chemistry, salt refers to a class of compounds that combine metal ions or ammonium ions (NH?+) with acid 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 generating sodium sulfate and water, and other reactions can generate salt, such as displacement reaction.
Salt is divided into single salt and combined salt, single salt is divided into normal salt, acid salt and basic salt, and combined salt is divided into complex salt and complex salt. The acid salt contains not only metal ions and acid radical ions, but also hydrogen ions. The basic salt contains not only metal ions and acid radical ions, but also hydroxyl ions. When the compound salt is dissolved in water, it can generate a complex salt with the same ions as the original salt; When the complex salt is dissolved in water, it can form complex salt complexes of complex ions different from the original salt.
Generally, under standard conditions, insoluble salt will be solid, but there are exceptions, such as molten salt and ionic liquid. Soluble salt solution and molten salt have conductivity, so they can be used as electrolytes. There are many different salts in the cytoplasm of cells, blood, urine and mineral water.