When metals react with acids, they produce salts and hydrogen gas. The general chemical equation for this reaction is:

Metal + Acid → Salt + Hydrogen gas

For example, when iron metal reacts with hydrochloric acid, the following reaction occurs:

Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)

In this reaction, iron metal reacts with hydrochloric acid to produce iron(II) chloride salt and hydrogen gas.