Percentage Yield

Theoretical yield is how much of the product is produced in an ideal situation (this is what was calculated in the using limiting reagents section of this website.) However, we don’t live in an ideal world and the amount that is actually produced is less than predicted. This is known as the actual yield.

In order to calculate the percentage yield you need only these formulas -
Percentage Yield=  Actual Yield/Theoretical Yield * (100)
Theoretical Yield = (Molar Mass of Product/Molar Mass of Reactant)*(Mass of Reactant)

In order to solve for the first formula, you must first solve the second and then plug in the value for Theoretical Yield to the first.

Example:

For the balanced equation shown below, if the reaction of 53.5 grams of N2O produces a 49.9% yield, how many grams of N2 would be produced ?
2N2O=>2N2+O2

First, we plug in values for the first formula...
Percentage Yield=  Actual Yield/Theoretical Yield * (100)
49.9% = Actual Yield/Theoretical Yield * (100)

Next, we plug in for the second formula...

Theoretical Yield = (Molar Mass of Product/Molar Mass of Reactant)*(Mass of Reactant)
Theoretical Yield = (56/88) * (53.5)
Theoretical Yield = 34

Lastly, we take the value for Theoretical Yield and plug it back into the first formula. Percentage Yield=  Actual Yield/Theoretical Yield * (100)
49.9% = (Actual Yield/34) * (100)
49.9% = 100x/34

X = 16.966