Chemical yield

A chemical yield states how much specified material is obtained after a chemical reaction or separation, relative to an explicitly stated reference amount.^[ref] In synthetic chemistry, the reference is commonly the theoretical product amount allowed by the limiting reactant and stoichiometry:For $2A\to B$, starting with $0.10$ mole of $A$ permits at most $0.050$ mole of $B$. Isolating $0.040$ mole gives $80\%$ yield. An isolated yield includes workup losses; an assay yield measures product in a mixture. Neither is automatically the same as reactant conversion, and a reported yield needs a purity and measurement convention.