1. Limiting reactants and Theoretical Yield
·How to recognize when you have a Limiting Reactant problem: In the problem will be given the mass or moles of two (2) reactants.
·You must decide which reactant is used up first. That is the limiting reactant. The limiting reactant gives the least amount of Product (Theoretical Yield).
·The process:
1) Calculate the mass of product possible from each reactant. Use the roadmap.
2) Compare the two results to see which gives the least amount of product. (theoretical yield)

2. Limiting reactants and Theoretical Yield
·The calculation that gives the least amount of product is from the Limiting Reactant.
·Theoretical Yield is the mass of product calculated from the limiting reactant.
·The excess reactant will be the one that produces the most product.

3. Sample Prob E pg. 314 PCl3 + 3H2O --> H3PO3 + 3HCl 225 g PCl3
1mol PCl3
1mol H3PO3
82.00 g H3PO3
225 g PCl3
1mol H3PO3
g PCl3
1mol PCl3
=134 g H3PO3
1mol H3PO3
82.00 g H3PO3
123g H2O
1mole H2O
1mol H3PO3
18.02 g H2O
3mole H2O
=187 g H3PO3
Limiting = PCl3 (produces the least product)
Theoretical Yield = 134g H3PO3
Excess = H2O

4. Limiting = PCl3 (produces the least product)
Sample Prob E pg. 314
Results:
225 g PCl3
would produce
134 g H3PO3
187 g H3PO3
123g H2O
would produce
Limiting = PCl3 (produces the least product)
Excess = H2O
Theoretical Yield = 134g H3PO3