Hydrochloric acid (hydrochloric acid) is an aqueous solution of hydrogen chloride (HCl), which is a strong monobasic inorganic acid and has a wide range of industrial uses. Hydrochloric acid is a colorless and transparent liquid with a strong pungent odor and high corrosiveness. Concentrated hydrochloric acid (about 37% by mass) is extremely volatile, so hydrogen chloride gas will volatilize after opening a container containing concentrated hydrochloric acid, and combine with water vapor in the air to produce small droplets of hydrochloric acid, causing acid to appear above the bottle mouth. fog. Hydrochloric acid is the main component of stomach acid, which can promote food digestion and resist microbial infections.
In the 16th century, Lipafius officially recorded the preparation of hydrogen chloride. Later, chemists such as Graub, Priestley, and David also used hydrochloric acid in their research.
During the Industrial Revolution, mass production of hydrochloric acid began. In the chemical industry, hydrochloric acid has many important applications, which play a decisive role in the quality of products. Hydrochloric acid can be used to pickle steel, and it is also a chemical reagent required for the large-scale preparation of many inorganic and organic compounds, such as vinyl chloride, the precursor of PVC plastics. Hydrochloric acid also has many small-scale uses, such as household cleaning, production of gelatin and other food additives, scale removal reagents, and leather processing. Approximately 20 million tons of hydrochloric acid are produced globally every year.
On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization was preliminarily compiled for reference. Hydrochloric acid was included in the list of three types of carcinogens, that is, the evidence of carcinogenicity to humans was insufficient.