Percent yield calculator: reaction yield and sample purity
Percent yield in its three directions (actual vs theoretical), sample purity, molar mass and conversion into moles.
Result
50 %
- Calculation
- yield = obtained / theoretical × 100 = 9.01 / 18.02 × 100 = 50%
- Theoretical amount
- 18.02
- Amount obtained
- 9.01
- Amount lost
- 9.01
- Molar mass
- 180.159 g/mol
- Theoretical amount in moles
- 0.100 023
- Amount obtained in moles
- 0.050 011 4
Note
The yield is 50%. 9.01 is missing against the prediction.
Calculation, assumptions and sources
OverviewThe yield of a synthesis is computed in three directions: measured afterwards, amount expected at a known yield, or theoretical amount needed to obtain a wanted amount.
The yield of a synthesis is computed in three directions: measured afterwards, amount expected at a known yield, or theoretical amount needed to obtain a wanted amount. The product formula, optional, gives its molar mass and the amounts in moles. A fourth mode computes the purity of a sample. A yield above 100% is shown as is, with a warning.
Method & formulasyield = obtained / theoretical × 100
The first three lines are a single equation, solved for each of its three unknowns.
- Theoretical amount
- what stoichiometry predicts from the limiting reagent, assuming the reaction goes to completion.
- Amount obtained
- what the balance gives after purification and drying.
- Yield
- the ratio of the two, as a percentage; both amounts must be in the same unit.
- Purity
- the share of the weighed mass that is the wanted product; the rest is solvent, water or impurity.
- M
- molar mass of the product, in g/mol, computed from its formula.
Validity domainThe theoretical amount comes from the limiting reagent; computed on a reagent in excess, it gives a falsely low yield.
The theoretical amount comes from the limiting reagent; computed on a reagent in excess, it gives a falsely low yield. A measured yield above 100% is physically impossible; it is shown uncorrected, with its three ordinary causes: a damp product, a weighing that includes the support, a theoretical amount computed on the wrong reagent. A yield entered as data is refused above 100%. The molar mass uses the IUPAC standard atomic weights, with the tool convention for the fourteen interval elements.
Reading the resultLosses in the mother liquor, on the glass, in filtration and in recrystallisation keep the yield below 100%.
Losses in the mother liquor, on the glass, in filtration and in recrystallisation keep the yield below 100%. Over a multi-step synthesis, yields multiply: three steps at 80% give 51%. Mass and molar yields are equal for the same substance, the molar mass cancelling; they differ between a reagent and a product.