PERCENT YIELD
~ compares
the actual amount of product that you made (in an experiment) to the amount of
product you should have made
~ ACTUAL
YIELD: amount of product that you made
in an experiment
~
THEORETICAL YIELD: amount of product that
you should have made (according to
calculations)
~ % YIELD = ACTUAL YIELD X 100
THEORETICAL YIELD
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EXAMPLE
What is the percent yield if a student makes 5.2 grams
of carbon dioxide by decomposing 9.5 grams of aluminum bicarbonate?
___ Al(HCO3)3 à
___ Al2O3
+ ___ CO2 + ___
H2O
ANSWER:
_2_
Al(HCO3)3 à
___ Al2O3
+ _6_ CO2 + _3_
H2O
9.5 g ? g
* I am
given the actual yield in the problem; I need to find the theoretical yield.
*
9.5 g Al(HCO3)3 | 1 mole Al(HCO3)3
| 6 moles CO2 |
44 g CO2 = 6.0 g CO2
| 210 grams | 2 moles Al(HCO3)3
| 1 mole CO2
So, 6.0 g
is the theoretical yield.
% yield = 5.2 g x 100 = 87 %
6.0 g
PRACTICE
PROBLEM
What is
the percent yield if a student produces 3.7 grams of water by reacting 7.5
grams of oxygen with excess hydrogen?
___ H2 +
___ O2 à ___ H2O