The balanced equation is as follows; 2H₂ + O₂ ---> 2H₂O the mass of water molecules formed - 1.8 g Therefore number of water molecules produced - 1.8 g / 18 g/mol = 0.1 mol Stoichiometry of H₂ to H₂O is 2:2 therefore number of hydrogen moles reacted = number of water moles formed number of H₂ moles produced - 0.1 mol therefore mass of H₂ - 0.1 mol x 2 g/mol = 0.2 g
