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How It Works
Percent yield compares the amount of product actually obtained in a chemical reaction to the maximum predicted by stoichiometry. A higher percent yield means less product was lost to side reactions, incomplete conversion, or purification steps.
Example Problem
A reaction has a theoretical yield of 25 g but produces only 19.5 g. What is the percent yield?
- Percent yield: (19.5 / 25) × 100 = 78%
A 78% yield is common for multi-step organic synthesis.
Frequently Asked Questions
Why is percent yield less than 100?
Reactions rarely reach 100% because of incomplete conversion, side reactions, and product lost during filtration or purification. Yields of 70–90% are typical for well-optimized reactions.
Can percent yield be over 100%?
A result above 100% usually means the product contains impurities (such as residual solvent or unreacted starting material) that add to its weight, or there is a measurement error.
How is percent yield different from percent error?
Percent yield measures reaction efficiency (actual vs. theoretical product). Percent error measures measurement accuracy (measured vs. accepted value). They use similar formulas but apply to different contexts.
Related Calculators
- Percent Error Calculator — compare a measured value to an accepted standard.
- Percent Difference Calculator — compare two experimental values without a standard.
- Statistics Calculator — analyze multiple yield measurements with mean and standard deviation.
- Density Calculator — verify product purity by comparing measured and theoretical densities.
- Mass Unit Converter — convert between grams, kilograms, and moles for yield calculations.