Dilute hydrochloric acid, i.e., hydrochloric acid with a mass fraction of less than 20%, has the chemical formula for the solute, HCl. Dilute hydrochloric acid is a colorless, clarified liquid that is strongly acidic. It has a pungent odor and belongs to pharmaceutical excipients, pH adjusters.

Dilute hydrochloric acid can be used to remove scale in boiling water (chemical equation) CaCO3 + 2HCl = CaCl2 + H2O + CO2 ↑ and Mg (OH) 2 + 2HCl = MgCl2 + 2H2O), the laboratory to produce carbon dioxide for (chemical equation): CaCO3 + 2HCl = CaCl2 + H2O + CO2 ↑, and iron, magnesium and other metals Reaction with iron, magnesium and other metals to generate a small amount of hydrogen needed for chemical experiments (chemical equation: Fe (Mg) + 2HCl = FeCl2 + H2 ↑).