Stoichiometry Module: Limiting Reactants

The only difference between these two problems is the units that the reactant amounts are given in. The problem on the left gives the reactants in mole quantities while the problem on the right gives the reactants in gram quantities. Because the balanced chemical equation relates mole quantities and not mass quantities, the problem on the right is relatively easy to do by inspection. If the reactant amounts in the problem on the left are converted to moles, the two problems are essentially the same.

To determine which reactant will limit the reaction, follow these steps:

Step 1: If reactant amounts are given in a unit other than moles, convert to moles.

Step 2: Choose one of the reactants and calculate how much of the other reactant is needed to react completely with the amount initially present.

Step 3: Compare the needed amount to the amount actually present.

Step 4: Using the amount of limiting reactant initially present, calculate the amount of product that can be formed.