Theoretical mass

This prediction is called the theoretical mass. It assumes that the reaction goes to completion, that the relevant reactant is completely used and that none of the product is lost. A laboratory result may be smaller; comparing an actual yield with the theoretical yield belongs to percentage-yield calculations.

A balanced chemical equation lets chemists predict how much product should be made from a known mass of reactant. This prediction is the theoretical mass: the maximum mass expected if the stated reactant reacts completely as shown by the equation, with enough of every other reactant available.