Transcript Percent Yield

Minds On…
• The reaction of potassium tetrachloroplatinate II (K2PtCl4)
with potassium iodide (KI) is used to make the cancer
drug Cisplatin. Given that platinum is very expensive,
which of the 2 reactants would you want to be limiting?
Explain.
Percent Yield
LG: Given values for the theoretical and actual yield, I can
determine the percent yield in a chemical reaction
Theoretical vs. Actual Yield
• Predicted mass of product, based on
stoichiometric calculation, is the theoretical yield
(maximum possible amount of product)
• Mass of product obtained during a chemical
reaction is the actual yield.
– Depressing chemistry fact: Actual yield is almost
always less than the theoretical yield
– Actual yield can never be greater than the theoretical
yield
Percent Yield
• Percent yield = (actual yield ÷ theoretical yield) × 100
• Percent yield can also be calculated using actual and
theoretical amounts in moles.
Example
• In an experiment, 5.00g of silver nitrate is added to a
solution containing excess sodium bromide. It was found
that 5.03g of silver bromide was produced. Determine
the percentage yield.
Factors Lower Percent Yield
1) Reverse reaction may be using products as they
are created
2) Some chemical always lost: spillage, splatter,
stuck to glassware, etc.
3) Chemical impurities: Reactants always contain
some impurities that make the predicted amount
of product impossible to achieve
Homework
• Text: Pg. 330 # 7, Pg. 339 # 3-5, 7-9, 13, 14
• Pre-lab: write balanced equation, complete
theoretical yield calculation, and familiarize
yourself with procedure