If a problem mentions amounts of more than one reactant, its probably a limiting reactant problem.
- Go from each reactant to amount of product (grams of each reactant to grams of product)
- The reactant that produces the lower amount of predicted product is the limiting reactant. This amount of product is also the amount that can be produced.
- The other reactant is your excess reactant.
Fe + S à FeS
If I have 28g of Iron (56 g/mol) and 24g of Sulfur (32 g/mol), how much FeS can be made and what is the limiting reactant?
g Fe x 1 mol Fe x 1 mol FeS x 87.92g FeS = 44 g FeS
g Fe 1 mol Fe 1 mol FeS
g S x 1 mol S x 1 mol FeS x 87.92g FeS = 66 g FeS
g S 1 mol S 1 mol FeS
Fe is the Limiting reactant because it runs out first and produces less FeS.