The balanced equation for the above reaction is as follows; 4HCl + O₂ ---> 2H₂O + 2Cl₂ stoichiometry of HCl to O₂ is 4:1 number of HCl moles present - 63.1 g / 36.5 g/mol = 1.73 mol number of O₂ moles present - 17.2 g / 32 g/mol = 0.54 mol if HCl is the limiting reactant; then number of O₂ moles = 1.73/4 = 0.43 mol There are 0.54 mol present and only 0.43 mol are required to react. Therefore HCl is the limiting reactant and O₂ is in excess.
