Answer : The theoretical yield of potassium carbonate is, 146.483 g
The percent yield of potassium carbonate is, 85.33 %
Solution : Given,
Mass of  = 150 g
 = 150 g
Mass of  = 90 g
 = 90 g
Molar mass of  = 212.27 g/mole
 = 212.27 g/mole
Molar mass of  = 233.99 g/mole
 = 233.99 g/mole
Molar mass of  = 138.205 g/mole
 = 138.205 g/mole
First we have to calculate the moles of  and
 and 


The given balanced reaction is,

From the given reaction, we conclude that
2 moles of  react with 1 mole of
 react with 1 mole of 
0.7066 moles of  react with
 react with  moles of
 moles of 
But the moles of  is, 0.3846 moles.
 is, 0.3846 moles.
So,  is an excess reagent and
 is an excess reagent and  is a limiting reagent.
 is a limiting reagent.
Now we have to calculate the moles of  .
.
As, 2 moles of  react to give 3 moles of
 react to give 3 moles of 
So, 0.7066 moles of  react to give
 react to give  moles of
 moles of 
Now we have to calculate the mass of  .
.


The theoretical yield of potassium carbonate = 146.483 g
The experimental yield of potassium carbonate = 125 g
Now we have to calculate the % yield of potassium carbonate.
Formula for percent yield :


Therefore, the % yield of potassium carbonate is, 85.33%