Zinc reacting with acid. Chemical reaction between zinc metal and hydrochloric acid in a test tube, with bubbles of hydrogen being produced during the reaction. Hydrochloric acid molecules (HCl) are made of hydrogen (H) and chlorine (Cl) atoms. The zinc (Zn) metal is more reactive than hydrogen and replaces it to make soluble zinc chloride (ZnCl2). Each displaced hydrogen atom combines with another to form hydrogen gas (H2). The equation for this reaction is: Zn + 2HCl -----> ZnCl2 + H2 Zinc chloride is used as a wood preservative, in electrical batteries, in dental fillings and as a dehydrating agent.