Here's why:

* HCl itself is the chemical formula for hydrogen chloride, a gas.

* When dissolved in water, HCl ionizes to form hydronium ions (H₃O⁺) and chloride ions (Cl⁻), making it acidic.

* The "hydro-" prefix in hydrochloric acid refers to the presence of hydrogen, and the "-ic" suffix indicates that it's an acid.