Percent yield calculatoris very useful tool for evaluating effectiveness a reaction in which all the reactant is not converted to product. This tool uses theoretical yield and actual yield formulas. When all the limiting reagent is converted to a product we may get the theoretical yield which is used to find percent yield.
Example 1:-
Find the Percent yield when 200.0 g N2 gas and 50.0g H2ismixed, they react to form ammonia gas
57.92g.
Solution 1:- N2 + 3H2à 2NH3
The initial amount of Nitrogen and hydrogen are
H2 = 50.0g x 1/2.016 = 24.8 mol
N2 = 200.0g x1/28.02 = 7.138 mol
There is excess of hydrogen. The theoretical yield will be
n Ammonia = 7.138 x 2/1 = 14.276 mol NH3
m Ammonia = 14.276 x 17.03/1 = 243.2 g NH3
Percent yield = (actual yield/theoretical yield)x100 = 57.92/243.2 x100 = 23.81 %
Example 2:-
Find the Percent yield when 384 g sulfur and oxygen is reacted to form 680g SO2 gas
Solution 1:- S6 + 6O2à6SO2
The initial amount of carbon
C = 384.0g x 1/192 = 2.0 mol
Total moles will be 2x6 = 12 moles of S6
There is excess of oxygen. The theoretical yield will be
Ammonia = 12 x 64/1 = 768 g SO2
Percent yield = (actual yield/theoretical yield)x100 = 680/768 x100 = 89 %