To determine the limiting reagent, you must first determine the balanced equation for the chemical reaction. Convert every unit given into moles, then adjust the balanced equation for every one of the reagents. Use stoichiometry to convert the resulting amounts of product into mass units. Compare the values. Whichever reagent produced the least amount of product is the limiting reagent.
- Look for the balanced chemical equation
Determine the balanced equation for the reaction given. Adjust the amount of the substances used in the chemical equation until you have the same number of atoms of each element on both sides.
- Convert all the amounts given into moles
Use the molar mass of each element or compound to convert all the given amounts from grams into moles. For example, 64 grams of O2 is equal to 2 moles of O2 because O2 has a molar mass of 32 grams per mole.
- Compute how much product is produced by each individual reagent
Use the balanced chemical equation to find out the amount of product each reactant can produce. Apply stoichiometry principles to determine the mass of the product in each situation.
- Compare the amounts of the products
Compare the resulting amounts and determine which is higher. The reactant that produces the least amount of product is the limiting reagent.