The equation shows the reaction between zinc metal and hydrochloric acid. Zn(s) + 2hcl(aq) right arrow. Zncl2(aq) + h2(g) what is the theoretical yield of hydrogen gas if 5. 00 mol of zinc are added to an excess of hydrochloric acid? 5. 05 g 10. 1 g 182 g 682 g.