Limiting Reactant & Theoretical Yield Calculator
Limiting Reactant & Theoretical Yield Calculator
In a chemical reaction, the limiting reactant is whichever reagent runs out first, stopping the reaction and determining the maximum ("theoretical") amount of product that can form. Enter both reactants and the product from your balanced equation to find out which one limits the reaction.
Finding the limiting reactant means converting each reactant's mass to moles, then dividing by its coefficient in the balanced equation — whichever reactant gives the smaller result runs out first and is the one that limits the reaction, regardless of how much excess of the other reagent remains unused. The theoretical yield is calculated entirely from that limiting reactant, since the reaction has to stop the instant it's used up, which is why stoichiometry problems in real lab settings almost always require identifying the limiting reactant before the actual yield can be predicted or compared against what was measured.
- Convert each reactant's mass to moles, then divide by its coefficient in the balanced equation - whichever gives the smaller result is the limiting reactant.
- The theoretical yield is calculated entirely from the limiting reactant, since the reaction stops once that reagent is used up, regardless of how much excess of the other reactant remains.
- Example: 2H₂ + O₂ → 2H₂O - with 4 g H₂ (2 mol, coefficient 2) and 32 g O₂ (1 mol, coefficient 1), both ratios come out almost equal, so this is a stoichiometrically balanced ("perfect") mixture.
How do I find the limiting reactant?
Convert each reactant's given mass to moles using its molar mass, divide by its coefficient in the balanced equation, and whichever gives the smallest number is the limiting reactant.
How do I calculate theoretical yield once I know the limiting reactant?
Multiply the limiting reactant's mole ratio by the product's coefficient, then multiply by the product's molar mass to get the theoretical yield in grams.
Limiting Reactant & Theoretical Yield Calculator
In a chemical reaction, the limiting reactant is whichever reagent runs out first, stopping the reaction and determining the maximum ("theoretical") amount of product that can form. Enter both reactants and the product from your balanced equation to find out which one limits the reaction.
Finding the limiting reactant means converting each reactant's mass to moles, then dividing by its coefficient in the balanced equation — whichever reactant gives the smaller result runs out first and is the one that limits the reaction, regardless of how much excess of the other reagent remains unused. The theoretical yield is calculated entirely from that limiting reactant, since the reaction has to stop the instant it's used up, which is why stoichiometry problems in real lab settings almost always require identifying the limiting reactant before the actual yield can be predicted or compared against what was measured.
- Convert each reactant's mass to moles, then divide by its coefficient in the balanced equation - whichever gives the smaller result is the limiting reactant.
- The theoretical yield is calculated entirely from the limiting reactant, since the reaction stops once that reagent is used up, regardless of how much excess of the other reactant remains.
- Example: 2H₂ + O₂ → 2H₂O - with 4 g H₂ (2 mol, coefficient 2) and 32 g O₂ (1 mol, coefficient 1), both ratios come out almost equal, so this is a stoichiometrically balanced ("perfect") mixture.
How do I find the limiting reactant?
Convert each reactant's given mass to moles using its molar mass, divide by its coefficient in the balanced equation, and whichever gives the smallest number is the limiting reactant.
How do I calculate theoretical yield once I know the limiting reactant?
Multiply the limiting reactant's mole ratio by the product's coefficient, then multiply by the product's molar mass to get the theoretical yield in grams.