Write down the formula of ethanol: CH3CH2OH . Then the reaction equation: CH3CH2OH + 3O2 ----> 2 CO2 + 3H2O Calculate the molar mass of ethanol, which is 46.0 g mol-1. Then calculate the number of moles of ethanol using equation n=m/Mr, which is 1.6 mol. Using the stoichiometry, we can deduce that the number of moles of carbon dioxide is 2 × 1.6 mol = 3.2 mol.