Answer: The mass of ester produced would be, 7.92 grams.
Explanation : Given,
Mass of butanoic acid = 7.70 g
Molar mass of butanoic acid = 88 g/mol
Molar mass of ethyl butyrate = 116 g/mol
First we have to calculate the moles of butanoic acid.


Now we have to calculate the moles of 
The balanced chemical equation is:

From the balanced reaction we conclude that
As, 1 mole of
react to give 1 mole of 
So, 0.0875 mole of
react to give 0.0875 mole of 
Now we have to calculate the mass of 


To calculate the amount of ester formed When the yield 78.0 % is calculated as follows:

Theoretical yield = 10.15 g
Now put all the given values in this formula, we get:


Therefore, the mass of ester produced would be, 7.92 grams.