Question

Consider the balanced equation. 2HCl + Mg mc031-1.jpg MgCl2 + H2 If 40.0 g of HCl react with an excess of magnesium metal, what is the theoretical yield of hydrogen?

Answer 1

M(HCl) = 35.5 +1.0 =36.5 g/mol
40.0 g HCl *1mol/36.5 g = 1.095 mol

                                 2HCl +Mg -----> MgCl2 + H2   
                                 2 mol                               1 mol
                               1.095 mol                          x mol

1.095 mol * 1mol/2 mol = 0.5479 mol H2

M(H2) = 2*1.0 = 2.0 g/mol

0.5479 mol H2 *2.0g/1 mol = 1.1 g H2

 The theoretical yield of hydrogen is 1.1 g