1. Stoichiometry: Percent Yield

2. What We Know You now know how to calculate the amount of product formed when specified amounts of reactants are mixed together. You know that the amount of product formed is controlled by the limiting reactant. –Products stop forming when the limiting reactant runs out

3. Theoretical Yield The amount of product formed in these calculations is called the theoretical yield. Theoretical yield is the amount of a given product that can be formed when the limiting reactant is completely consumed.

4. Theoretical Yield In stoichiometry problems you are predicting the maximum amount of product that can be produced. In reality, the maximum amount is rarely obtained. –This could be due to side reactions, human error, or various other causes.

5. Actual Yield The amount of product you actually obtain in a chemical reaction is called the actual yield. This is the amount you measure in the lab, not what you calculated in a stoichiometry problem.

6. Percent Yield Percent yield is the actual yield of a product as a percentage of the theoretical yield. Gives you a comparison between what you thought would be produced (theoretical yield) and what actually was produced (actual yield).

7. Percent Yield Actual Yield / Theoretical Yield x 100 = Percent Yield Divide the actual yield by the theoretical yield and multiply by 100 to get the percent yield.

8. Practice Problem Methanol (CH 3 OH) can be produced by the reaction between carbon monoxide and hydrogen. Suppose 6.85 x 10 4 g of carbon monoxide is reacted with 8.60 x 10 3 g of hydrogen. What is the theoretical yield of methanol? If 3.57 x 10 4 g of methanol is actually produced, what is the percent yield of methanol?

9. Practice Problem Titanium (IV) oxide is a white compound used as a coloring pigment. In fact, the pages in your textbook are white because of the presence of this compound in the paper. Solid titanium (IV) oxide can be prepared be reacting gaseous titanium (IV) chloride with oxygen gas. A second product of this reaction is chlorine gas. If 6.71 x 10 3 g of titanium (IV) chloride reacts with 2.45 x 10 3 g of oxygen, what is the mass of titanium (IV) oxide that can form? If the percent yield of titanium (IV) oxide is 75%, what mass is actually formed?