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Percent yield

Percent yield shows how much product actually forms in a reaction, compared to the theoretical maximum calculated from stoichiometry. It is rarely 100% in practice, due to side reactions, incomplete reaction, or losses during purification.

\text{yield} = \frac{\text{actual amount}}{\text{theoretical amount}}\times 100\%

percent yield

Example

Theoretical 87.8 g CO2 expected, but only 80 g forms:

Yield $= (80/87.8)\times 100 \approx 91\%$ .

Always calculate the theoretical yield from the limiting reactant, not from a reagent in excess.

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