We'll practice limiting reactant and excess reactant by working through a problem. These are often also called limiting reagent and excess reagent. The limiting reactant or the limiting reagent is the first reactant to be used up during a chemical reaction. Once the limiting reactant or limiting reagent is used up, no more product can form. In order to solve stoichiometry problems with limiting reactant or limiting reagent, we need to figure out which of the reactants is the limiting reactant or limiting reagent. Then, we see how much product can be formed by using the maximum amount of the limiting reactant or limiting reagent. The excess reactant or excess reagent is what is left over after all of the limiting reactant or limiting reagent has been used up.