1. Limiting reagents In lab a reaction is rarely carried out with exactly the required amounts of each reactant. In lab a reaction is rarely carried out with exactly the required amounts of each reactant. Once one reactant is used up, no more product can be formed. Once one reactant is used up, no more product can be formed.

2. Limiting reactant – the reactant that limits the amount of product that can form in a chemical reaction. Limiting reactant – the reactant that limits the amount of product that can form in a chemical reaction. Excess reactant – The substance that is not used up completely in a reaction. Excess reactant – The substance that is not used up completely in a reaction.

3. Limiting Reactant Steps Choose one Given Choose one Given Calculate the amount NEEDED of other reactant (stoichiometry) Calculate the amount NEEDED of other reactant (stoichiometry) Compare the amount of the other reactant you have with the NEEDED amount Compare the amount of the other reactant you have with the NEEDED amount If what you: If what you: Have > NEEDED =>Excess reactant Have Limiting reactant

4. Practice Problem 35.4 g of sodium chloride and 99.8 g of silver nitrate are mixed forming sodium nitrate and silver chloride. Which substance is in excess?

5. Percent Yield The percent yield is the ratio of the actual yield to the theoretical yield, multiplied by 100 The percent yield is the ratio of the actual yield to the theoretical yield, multiplied by 100 Percent Yield = Actual yield x100 Theoretical yield

6. Practice Problem What is the percent yield of the product if 8.71 grams of copper is produced when 2.82 grams of aluminum is reacted with an excess of copper(II) sulfate?