Calculate the theoretical yield (in grams of acetic acid, FW 60.05 g/mol) if 8.79 mL of acetic anhydride (FW 102.09 g/mol, density 1.08 g/mL) is used.

Question

When acetic anhydride is dissolved in water, it forms acetic acid according to the balanced chemical reaction shown below. Calculate the theoretical yield (in grams of acetic acid, FW 60.05 g/mol) if 8.79 mL of acetic anhydride (FW 102.09 g/mol, density 1.08 g/mL) is used. You can assume that the water is present in excess.

Answer 1

Hello Aspen

 

The balanced chemical reaction for the hydrolysis of acetic anhydride to acetic acid can be written as:

 

(CH₃CO)₂O (l) + H₂O (l) → 2 CH₃COOH (l)

 

First, we need to convert volume of acetic anhydride to mass using its density.

 

d = m / V

 

m = d x V = 1.08 x 8.79 = 9.49 g

 

Now use stoichiometry to convert mass of acetic anhydride to mass of acetic acid, which will be the theoretical yield.  Mole ratio of acetic anhydride to acetic acid is 1:2.

 

9.49 g anhydride x (1 mol anhydride / 102.09 g anhydride) x (2 mol acid / 1 mol anhydride) x (60.05 g acid / 1 mol acid)  =  11.2 g acetic acid