Theoretical Yield Calculator

The calculation of theoretical yield relies on the fundamental conservation of mass and molar ratios defined by a balanced chemical equation. First, we find the moles of your limiting reactant by dividing its given mass by its molecular weight: Limiting Moles = Limiting Mass / Limiting Molecular Weight. Next, we apply the stoichiometric coefficients from the balanced equation to find the moles of the desired product: Desired Moles = (Limiting Moles / Limiting Stoichiometry) * Desired Stoichiometry. Finally, we convert these moles back into a mass by multiplying by the molecular weight of the product: Desired Yield = Desired Moles * Desired Molecular Weight.

Imagine you are combusting hydrogen gas in the presence of oxygen, described by the balanced reaction: 2H2 + O2 -> 2H2O. Suppose you start with 10 grams of hydrogen gas as your limiting reactant, with a molecular weight of 2.016 g/mol. Hydrogen has a stoichiometric coefficient of 2, and the desired product water (H2O, molecular weight 18.015 g/mol) also has a coefficient of 2. First, calculate the moles of hydrogen: 10 g / 2.016 g/mol = 4.96 moles. Since the stoichiometric ratio is 2:2 (or 1:1), you will also produce 4.96 moles of water. Multiplying these moles by the molecular weight of water gives your theoretical yield: 4.96 moles * 18.015 g/mol = 89.35 grams of water.

Always ensure your chemical equation is fully balanced before identifying stoichiometric coefficients; an unbalanced equation will immediately invalidate your output. Double-check the purity of your starting reagents, as impurities can alter the effective limiting mass. Finally, remember that theoretical yield represents a 100% efficient scenario, which rarely occurs in real-world labs due to side reactions or incomplete recovery.