wikiHow Theoretical Yield Calculator The theoretical yield is the amount of product that should be obtained in a chemical reaction based on the stoichiometry of the reaction and the limiting reactant. The steps to calculate theoretical yield are as follows: Write the balanced chemical equation for the reaction. Identify the limiting reactant, which is the reactant that is completely consumed in the reaction and limits the amount of product that can be formed. Determine the stoichiometry of the reaction, which is the ratio of the moles of reactants and products based on the coefficients in the balanced chemical equation. Calculate the amount of product that should be formed based on the amount of limiting reactant using stoichiometry. The calculated amount is the theoretical yield. Here is an example: Suppose we want to calculate the theoretical yield of carbon dioxide (CO2) when 25 grams of methane (CH4) react with excess oxygen gas (O2) according to the following balanced chemical equation: CH4 + 2O2 → CO2 + 2H2O The balanced chemical equation is given as CH4 + 2O2 → CO2 + 2H2O. In this case, the limiting reactant is methane (CH4) because it is consumed completely in the reaction. The stoichiometry of the reaction is 1 mole of CH4 reacts with 2 moles of O2 to produce 1 mole of CO2 and 2 moles of H2O. To calculate the theoretical yield, we first convert 25 grams of CH4 to moles using its molar mass: 25 g CH4 × (1 mol CH4/16.04 g CH4) = 1.56 mol CH4 Using stoichiometry, we can determine the amount of CO2 that should be produced: 1.56 mol CH4 × (1 mol CO2/1 mol CH4) = 1.56 mol CO2 Therefore, the theoretical yield of CO2 is 1.56 moles or the mass of CO2 can be calculated by multiplying the moles of CO2 by its molar mass. Page