1. Limiting Reactants & Percent Yield

2. Limiting Reactants  The reactant that limits the amount of product formed in a chemical reaction. The quantity of product is always determined by the quantity of limiting reactant.

3. Steps for Solving a Limiting Reactant Problem  1.Write the Balanced Equation  2.Calculate the number of moles of product from the given amount of the 1st reactant.  3. Calculate the number of moles of product from the given amount of the 2nd reactant.  4. Whichever reactant produced the fewest moles of product signifies the limiting reactant.  5. Convert Moles of Product to the required units.

4. Example  Combine hydrogen and oxygen to make water  H 2 + O 2  H 2 O  Given 2.0 grams of hydrogen and 10.0 grams of oxygen, determine the limiting reactant.

5. Balance your equation  __H 2 + __O 2  __H 2 O  Enter the coefficients to balance the equation. Remember to use 1 when needed.

6. To solve – find the amount of product made for each reactant  2H 2 + 1O 2  2H 2 O 2.0 g H 2 1 mole H 2 2 mole H 2 0 18 g H 2 0 = 18 g H 2 0 2 g H 2 2 mole H 2 1 mole H 2 0 10.0 g O 2 1 mole O 2 2 mole H 2 0 18 g H 2 0 = 11.25 g H 2 0 32 g O 2 1 mole O 2 1 mole H 2 0

7. How many grams of water are produced?  For the original problem, answer the problem.  Round your answer to the correct number of sig figs.

8. Percent Yield  % Yield = the percent of product actually produce in an experiment  % Yield= actual yield X 100  theoretical yield

9. Percent Yield Example  A chemist started with 10.0 grams of O 2 and 2.0 grams of H 2. She produces 6.9 grams H 2 O according to the following equation.  H 2 + O 2  H 2 O  Determine the percent yield for this reaction. (find the limiting reagent)