1. Chapter 12 Stoichiometry Part 3

2. PERCENT YIELD
Most reactions never succeed in producing the predicted amount of product. So in order to determine the success of a reaction, the percent yield is calculated.

3. * to determine if a method of manufacturing a product
Comparing the actual quantitative results of a chemical rxn to the theoretical (calculated) maximum.
Why?
* to determine if a method of manufacturing a product
is profitable or another method works better

4. Usually the % yield is less than 100 b/c product is lost
somewhere along the way or the reaction wasn’t complete.
Occasionally the % yield is above 100 if the product is
contaminated or if moisture is absorbed b/c of high humidity.

5. % yield = actual yield x 100 theoretical yield
theoretical  maximum amount of product that can be produced from a given amount of reactant in a chemical equation
actual  the amount of product actually produced when the chemical reaction is carried out in an experiment

6. Examples
When 24.8g of calcium carbonate is decomposed by heating, 13.1g of calcium oxide forms along with some CO2. What is the % yield of this rxn?

7. Example
What is the percent yield if 3.74g of copper are produced when 1.87g of Al are reacted with an excess of copper II sulfate?
2Al + 3CuSO4 → Al2(SO4)3 + 3Cu

8. Example
What is the percent yield if 56.15g of Na reacts with an excess of Cl2 and yields 136.2g of sodium chloride?

9. Example
If the decomposition of magnesium chlorate is 92.3% efficient, how many grams of magnesium chlorate are needed to produce g of magnesium chloride?