Theoretical Yield Calculator
Calculate the maximum product mass using reaction stoichiometry.
1. Reactant (Starting Material)
2. Product (Target)
Ready to Calculate
Enter reactant details to trace the stoichiometry path.
Predicting Chemical Potential
Before a chemist mixes a single drop in a beaker, they need to know what to expect. Theoretical Yield is that prediction—it answers the question: "If everything goes perfectly, how much product will I get?"
It serves as the benchmark for success. Without calculating the theoretical limit, you cannot know if your experiment was highly efficient or a complete failure.
The "Stoichiometry Bridge"
You cannot convert grams of one substance directly to grams of another. You must cross the "mole bridge". This calculator automates these three specific steps:
Mass to Moles
Divide grams by Molar Mass (g/mol).
Mole Ratio
Use Coefficients from the balanced equation.
Moles to Mass
Multiply moles by new Molar Mass.
Theoretical Yield
Final Maximum Mass
Important Definitions
- StoichiometryThe mathematics of chemistry. It deals with the quantitative relationships between reactants and products.
- Limiting ReagentThe reactant that runs out first. The theoretical yield is ALWAYS determined by the limiting reagent.
- Excess ReagentLeftover ingredients that do not contribute to the final product mass once the reaction stops.
Pro Tips for Students
Balance First!
Never start a calculation without a balanced equation. If the coefficients are wrong, the mole ratio (the bridge) collapses.
Check Units
Molar mass is always g/mol. Calculating with kilograms? Convert to grams first (multiply by 1000).
Sig Figs Matter
Your answer cannot be more precise than your starting measurement. Keep significant figures in mind for lab reports.
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Frequently Asked Questions
What is Theoretical Yield?
Theoretical Yield is the maximum amount of product that could be created from a given amount of reactant, assuming the reaction is perfect. It assumes 100% of the limiting reactant turns into product with no loss, no side reactions, and no impurities.
How do I calculate Theoretical Yield?
The process follows 3 main steps (stoichiometry):
- Convert Mass to Moles: Divide grams of reactant by its molar mass.
- Apply Mole Ratio: Multiply by (Coefficient of Product / Coefficient of Reactant).
- Convert Moles to Mass: Multiply the new moles by the product's molar mass.
Why is Theoretical Yield different from Actual Yield?
Theoretical yield is a calculation on paper (the ideal scenario). Actual yield is what you weigh on a scale after doing the experiment. Actual yield is almost always lower due to spills, evaporation, incomplete reactions, or purification losses.
Do I always need a balanced chemical equation?
Yes! The coefficients (the big numbers in front of formulas like 2H₂ + O₂ → 2H₂O) tell you the ratio in which molecules react. Without these, you cannot correctly convert between reactants and products.
What if I have two reactants? Which one do I use?
You must use the Limiting Reagent. Calculate the theoretical yield for both reactants. The one that produces the smaller amount of product is the correct answer, because the reaction stops once that ingredient runs out.
Can theoretical yield be in moles?
Yes. Theoretical yield can be expressed in moles (amount of substance) or grams (mass). Most lab questions ask for grams, but the calculation always passes through moles first.
Does the molar mass affect the yield?
Yes. A heavy product molecule will result in a higher mass yield for the same number of moles compared to a light product molecule. This is why we convert moles back to grams at the end.
What is the unit for theoretical yield?
The standard unit is grams (g) for mass, or moles (mol) for amount. In industrial settings, it might be calculated in kilograms (kg) or tonnes.
Is theoretical yield the same as Percent Yield?
No. Theoretical yield is the denominator in the percent yield formula. Percent Yield = (Actual / Theoretical) × 100%.
Can I use volume instead of mass?
If you are working with gases at STP (Standard Temperature and Pressure), you can use the conversion 1 mole = 22.4 Liters. If you have a solution, you use Molarity (Moles / Liter).