Zinc metal reacts with hydrochloric acid according to the following equation: Zn + 2HCl yields ZnCl2 + H2. How many grams of hydrogen gas can be obtained if 50.0 g of zinc react completely?
mols Zn = grams/molar mass
Convert mols Zn to mols H2 susing the coefficients in the balanced equation.
Now convert mols H2 to g. g = mols x molar mass.