Question

If 1.oo mol CS2 reacts with 1.00 mol O2 , identify the limiting reactant

Answer 1

moles of excess reactant remaining: 0.67 mol CS2

moles of each product formed: 0.33 mol CO2 and 0.67 mol SO2

your coefficients in the chemical equation reveal the molar ratio of the reactants that must be present to give a complete reaction of both reactants. in this case each mole of CS2 requires 3 moles of O2 to form the products given. if you start with equimolar amounts of both reactants then the O2 must be in insufficient supply to completely react with all of the CS2. if only 1 mole of O2 is present, it will be consumed by one third that amount of CS2. all O2 will react. 0.67 mole of CS2 will remain. the CO2 comes from the carbon in CS2, so 0.33 mole of CO2 will be produced. since 2 moles of SO2 are produced for each mole of CO2 produced, then the amount of SO2 produced will be 0.67 mol.