Minds On… The reaction of potassium tetrachloroplatinate II (K 2 PtCl 4 ) 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