<u>Answer:</u>
<u>For a:</u> The mass of acetic anhydride needed is 73.91 grams.
<u>For b:</u> The theoretical yield of aspirin is 130.43 grams.
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
- <u>For a:</u>
Given mass of salicylic acid =
Molar mass of salicylic acid = 138.121 g/mol
Putting values in equation 1, we get:
For the given chemical reaction:
By stoichiometry of the reaction:
1 mole of salicylic acid reacts with 1 mole of acetic anhydride.
So, 0.724 moles of salicylic acid will react with = of acetic anhydride.
Now, to calculate the mass of acetic anhydride, we use equation 1:
Moles of acetic anhydride = 0.724 moles
Molar mass of acetic anhydride = 102.09 g/mol
Putting values in equation 1, we get:
Hence, the mass of acetic anhydride needed is 73.91 grams.
- <u>For b:</u>
By stoichiometry of the reaction:
1 mole of salicylic acid is producing 1 mole of aspirin.
So, 0.724 moles of salicylic acid will produce = of aspirin.
Now, to calculate the mass of aspirin, we use equation 1:
Moles of aspirin = 0.724 moles
Molar mass of aspirin = 180.158 g/mol
Putting values in equation 1, we get:
Hence, the theoretical yield of aspirin is 130.43 grams.