Hydrogen chloride (HCl), a molecule of hydrogen chloride consisting of a chlorine atom and a hydrogen atom, is a colorless, irritating gas. Its aqueous solution is commonly known as hydrochloric acid and its scientific name is hydrochloric acid. The relative molecular mass is 36.46. Hydrogen chloride is very soluble in water. At 0 ° C, one volume of water can dissolve about 500 volumes of hydrogen chloride.
The aqueous solution of hydrogen chloride is hydrochloric acid.
- Used in the bleaching and dyeing industry (acid). For example, pickling after bleaching of cotton cloth, neutralization of residual alkali after mercerization of cotton cloth. During the printing and dyeing process, some dyes are insoluble in water and need to be treated.
- For metal processing (acid) For example, before plating of iron and steel parts, first wash with caustic soda solution to remove oil stains, and then soak with hydrochloric acid; before welding the metal, apply a little salt to the weld.
- Used in the food industry (catalytic) For example, when making chemical soy sauce, immerse raw materials such as cooked bean cake in a solution containing a certain amount of hydrochloric acid and maintain a certain temperature. After hydrolysis for a certain period of time, umami is produced, and then neutralized with caustic soda (or with) to obtain sodium. The principle of making MSG is similar.
- For the production of inorganic and organic drugs (acidic acid) Hydrochloric acid is a strong acid. It is related to certain metals, metal oxides, metal hydroxides and most metal salts (such as carbonates, sulfites, etc.). ), Can react.