Percent Yield and Percent Purity

Percent Yield
In chemical reaction, products are always not the same as in calculation. For example, in stoichiometry calculation, we are supposed to get 12g CaCO3 in this reaction: Ca(OH)2 + H2SO3 ------CaSO3 + 2H2O. But in fact we just get 8g. The reason might be impure reactants. Therefore, we have Percent Yield.


Percent Yield is the percentage of real mass we get by the calculation results.

% Yield = actual mass / calculation mass

Percent Purity
Same as the other substance. Sometimes the substance might not be absolute pure. For example, gold alwas contains impurities in it.

% Purity = pure mass / whole mass