Percent Yield Calculator

Find the limiting reagent, theoretical yield and percent yield.

Convert each reactant mass to moles and divide by its coefficient in the balanced equation. The reactant with the smallest value is the limiting reagent. Theoretical yield = that value × product coefficient × product molar mass. Percent yield = actual yield ÷ theoretical yield × 100.

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What you enter

What you get

Formula

n = m / M   |   limiting = min(nᵢ / aᵢ)   |   theoretical (g) = min(nᵢ / aᵢ) × b × M(product)   |   % yield = actual / theoretical × 100

aᵢ is the stoichiometric coefficient of reactant i and b the coefficient of the product. Dividing moles by the coefficient puts every reactant on the same scale, the number of times the reaction as written can run. The smallest of these runs out first and sets the maximum product.

Questions

How do you calculate percent yield?

Divide the actual yield by the theoretical yield and multiply by 100. If you expected 2.61 g of aspirin and collected 2.10 g, the percent yield is 2.10 ÷ 2.61 × 100 = 80.5 %.

How do you find the limiting reagent?

Convert each reactant to moles, then divide by its coefficient in the balanced equation. The smallest result is the limiting reagent. Comparing moles alone is wrong whenever the coefficients differ.

How do you calculate theoretical yield?

Take the limiting reagent's moles, multiply by the ratio of product coefficient to limiting reagent coefficient, then multiply by the product's molar mass.

Can percent yield be over 100 %?

Not for a pure, dry product. A value above 100 % usually means the product still contains solvent, water or a side product.

Can I type a formula instead of a molar mass?

Yes. Enter a formula such as C9H8O4 in any molar mass box and it is converted using IUPAC atomic weights.

References

More Chemistry

All free tools · By Dr. Zubair Khalid, DVM, MS, PhD.