1. *Notice, kind of like the opposite of Percent Error.
Percent Yield
*Notice, kind of like the opposite of Percent Error.

2. Percent Yield Problems
The amount of product produced from a reaction based on a calculation is the expected yield (or theoretical yield)
The amount of product that is really obtained during the reaction (in a lab or industrial setting) is the actual yield (real life)
It is useful to determine what percent of the expected yield was actually obtained.
percent yield = actual yield x 100%
expected yield

3. Potential reasons for differences between actual and expected yield
some reactants didn’t fully react
there were side reactions that differ from the reaction on which the expected yield was based
some product was lost during recovery or transfer

4. Example Problem
A reaction occurs between g of carbon disulfide and an excess amount of oxygen gas.
The actual mass of sulfur dioxide produced is 768 g. What is the percent yield for this reaction?
Step 1: Write the balanced equation.
CS2 + 2 O2  2 SO2 + C
Notice! You have plenty of oxygen, can use up all CS2, don’t worry about limiting reagent!

5. Example Problem CS2 + 2 O2  2 SO2 + C
Step 2: Determine the expected yield using stoichiometry
500.0 g CS2 x 1 mol CS2 x 2 mol SO2 x g SO2 = g SO2
76.15 g CS mol CS mol SO2
This is how much SO2 you should be able to produce (theoretical yield)

6. Example Problem CS2 + 2 O2  2 SO2 + C
Step 3: Compare the actual yield to the expected yield using the percent yield equation.
percent yield = actual yield x 100%
expected yield
Percent yield = g x 100% = % (of expected) g