Question: small quantities of hydrogen gas can be prepared by the addition of hydrochloric acid to zinc?
Answer: Small quantities of hydrogen gas can be prepared in the laboratory by the addition of aqueous hydrochloric acid to metallic zinc. Zn(s)+2HCl(aq)⟶ZnCl2(aq)+H2(g) Typically, the hydrogen gas is bubbled through water for collection and becomes saturated with water vapor.