# 7 3 reaction yields

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```					                                7.3 Reaction Yields
Learning Goals …

… use stoichiometry to determine the theoretical yield of a reaction
… determine the percent yield of a reaction given actual yield
… determine actual yield of a reaction given percent yield

Theoretical yield

• the amount of product predicted from stoichiometry.

Actual yield

• the amount of product that is obtained from the chemical reaction in an
experiment.
• this quantity is usually different from theoretical yield.
• sources of error  _____________________ of chemicals, products
________________ during heating, __________________ precipitates,
_____________________ solutions.

Percentage yield:

• compares the mass of the product predicted from stoichiometry with that
actually obtained from experiment.

• To calculate Percentage Yield:

Percentage yield =      actual yield    x 100%
theoretical yield

Ex.   When 245 kg of arsenic ore (FeSAs) was processed industrially, 95.3 kg of
pure arsenic was obtained. Calculate the percentage yield of arsenic in the
process.

FeSAs (s)            FeS (s)          +    As(s)
Ex.   In an experiment, when 16.1 g of FeS reacted with 10.8 g of oxygen gas, 14.1g
of iron(III) oxide was produced. Calculate the percentage yield of iron (III)
oxide in the experiment.

4 FeS        +    7 O2      2 Fe2O3    +     4SO2

Ex.   If the reaction proceeds with a 92.4% yield of calcium oxide, how many grams
of CaO will be obtained if 12.4 g of calcium carbonate is heated?

CaCO3 (s)                  CaO (s)     +      CO2 (g)

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