Theoretical Yield, Actual Yield, and Percent (%) Yield
Until now, you’ve been calculating the theoretical yield for a chemical reaction. You just didn’t
know you were doing it.
For example: How many grams of NH3 gas will 5 grams of Nitrogen (N2) produce?
N2
+
5g
3 H2

?g
mol
5 g N2
2 NH3
mol
1 mol N2
28 g N2
2 mol NH3
1 mol N2
17 g NH3
1 mol NH3
=
6.07 g NH3
“Theoretically” you just calculated that 6.07 grams of NH3 is produced in this reaction, so what
you calculated is the Theoretical Yield.
It turns out that most reactions do not go entirely to completion, so when you actually perform
this experiment in the lab, you will not “actually” make the amount you calculated above. The
amount of product that is actually produced through experimentation is called the actual yield.
Percent Yield (% Yield) can be found using the following formula.
% Yield
=
Actual Yield
Theoretical Yield
X 100
So remember:
Theoretical Yield is what you calculate will be made by the reaction. Ex. 6.07 g NH3
Actual Yield is what the problem stated was actually made after running the experiment
and measuring the amount of product made.
% Yield
=
Actual Yield
Theoretical Yield
X 100