PERCENTAGE YIELD
Yield
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The amount of product obtained by a chemical reaction.
Sometimes the yield is less than you would expect.
There maybe some product left behind at different stages in
the preparation.
Percentage yield = actual yield x 100%
predicted yield
Example
25 cm3 of ammonium hydroxide solution is
reacted to form the fertiliser ammonium sulfate
and the predicted yield is 3.30 g.
However, when chemists actually made this they
found 2.64 g was the mass produced.
What is the percentage yield?
Percentage Purity
In a similar way, percentage purity can be calculated.
The equation is:
Percentage purity = mass of pure substance x 100%
mass of impure product
Example
A sample of impure common salt had a
mass of 5.6 g. When purified, the mass of
sodium chloride produced was 4.2 g. What
is the percentage purity of the impure
sample?