If necessary calculate how much is left in excess of the non-limiting excess reactant. This chemistry video tutorial shows you how to identify the limiting reagent and excess reactant. To express the efficiency of a reaction you can calculate the percent yield using this formula.
Limited by the given amounts of reactants.
Part 1 Finding the Limiting Reactant. The reactants and products along with their coefficients will appear above. Percent yield actual yieldtheoretical yield x 100. Much time and money is spent improving the percent yield for chemical production.