1. Percent Yield and Limiting Reactants Using Reaction Stoichiometry

2. Percent Yield • % Yield= Actual Yield / Theoretical Yield x 100 • Actual Yield- from a lab (what was actually produced) • Theoretical Yield- from a reaction stoichiometry problem (mathematical value… what you should have gotten)

3. Percent Yield Practice PbS + O2PbO + SO2 • Balance the equation above. • What is the theoretical yield of PbO if 200.0g of PbS is reacted? • If 170.0g of PbO is obtained in a chemical reaction, what is the percent yield?

4. More practice… • Upon heating, solid calcium carbonate decomposes to form solid calcium oxide and carbon dioxide gas. • Write the complete balanced chemical reaction for the reaction. • Determine the percent yield if 235.0g of calcium carbonate is heated and 97.5g of carbon dioxide is collected.

5. Limiting Reactants • Limiting Reactant- the reactant (reagent) that produces the fewest moles of product. • Reaction can only form the amount of product “allowed” by the limiting reactant.

6. Limiting Reactant Steps • Balance the Equation • Use mole ratios to find the moles of a product formed by each reactant (using the amounts given in the problem) • The reactant that makes the smallest number of moles of product is the limiting reactant. The other is the excess reactant. • The smallest number of moles produced will be the actual amount of product formed in the reaction. To find excess reactant remaining: • Subtract the two amounts of product formed (from step #2 above) and use mole ratios convert back to the reactant.

7. Limiting Reactant Practice H2+ O2 → H2O • If 12.2 mol H2 and 8.4 mol O2 react… • What is the limiting reactant/reagent? The excess reactant? • How many moles of water are produced? • How many grams of water are produced? • How many moles of excess reactant remain?