Hydrochloric acid
Molar mass: 36.46 g/mol · Class: Strong acid
Elements: hydrogen, chlorine
Structure
Hydrogen chloride is a polar covalent molecule, with hydrogen bonded to chlorine. In water it ionizes completely into H+ (as hydronium) and Cl-, which is why its solutions are strongly acidic.
Properties
Strong acid: ionizes completely in water
Colorless solution with a sharp, pungent smell when concentrated
Reacts with most metals to release hydrogen gas
Concentrated solutions fume in moist air
Applications
Steel pickling to remove rust and scale
pH control in industry and pools
Production of chlorides and organic compounds
Stomach acid for digestion (dilute, in the body)
Corrosive: causes severe skin and eye burns. Vapors irritate the lungs. Always add acid to water, never the reverse, wear eye protection, and work with ventilation. Keep away from children.
Data source: IUPAC standard atomic weights 2021; molar mass computed from HCl