Theoretical Yield Calculator
Calculate the maximum theoretical amount of product that can be formed from a limiting reactant using stoichiometric coefficients and product molar mass.
Calculate Theoretical Yield
Enter the limiting reactant amount, balanced equation coefficients, and molar mass of the desired product.
Product moles = Reactant moles × (Product coefficient ÷ Reactant coefficient)
Theoretical yield = Product moles × Product molar mass
What Is Theoretical Yield?
Theoretical yield is the maximum calculated amount of product that can be formed from the available limiting reactant according to a balanced chemical equation.
It represents an ideal stoichiometric result. Experimental or actual yield may be lower because real experiments do not always convert every available reactant into the desired product.
Theoretical Yield Formula
When the amount of limiting reactant is already known in moles, first convert reactant moles into product moles using the coefficients from the balanced chemical equation.
How to Calculate Theoretical Yield
Identify the Limiting Reactant
Determine which reactant limits the reaction and convert its available amount to moles if necessary.
Apply the Mole Ratio
Use the balanced equation coefficients to convert limiting-reactant moles into desired-product moles.
Convert Moles to Grams
Multiply the calculated product moles by the product's molar mass to obtain theoretical yield in grams.
Theoretical Yield Calculation Variables
| Variable | Meaning | Typical Unit |
|---|---|---|
| n(reactant) | Moles of limiting reactant | mol |
| a | Limiting reactant coefficient | Dimensionless |
| b | Desired product coefficient | Dimensionless |
| n(product) | Theoretical product moles | mol |
| M | Product molar mass | g/mol |
| Theoretical Yield | Maximum calculated product mass | g |
Theoretical Yield Example
Example: Formation of Water
Consider the balanced equation: 2H₂ + O₂ → 2H₂O.
Suppose 2.00 mol H₂ is the limiting reactant.
H₂ coefficient = 2
H₂O coefficient = 2
Product molar mass ≈ 18.015 g/mol
Product moles = 2.00 × (2 ÷ 2) = 2.00 mol
Theoretical yield = 2.00 × 18.015 = 36.03 g
Theoretical Yield vs Actual Yield
Theoretical yield is calculated from stoichiometry, while actual yield is the amount of product obtained in an experiment.
| Type | Meaning | How It Is Found |
|---|---|---|
| Theoretical Yield | Maximum predicted product amount | Stoichiometric calculation |
| Actual Yield | Product amount actually obtained | Experimental measurement |
| Percent Yield | Comparison of actual and theoretical yield | Actual ÷ Theoretical × 100 |
Why Does the Limiting Reactant Matter?
The limiting reactant determines the maximum amount of product that can form. Once that reactant is consumed, the balanced reaction cannot produce additional product from the remaining excess reactants alone.
For this reason, theoretical yield calculations should be based on the limiting reactant rather than simply choosing any reactant from the equation.