How much salicylic acid would be required if only 53% of the salicylic acid is converted to aspirin?

Question

Aspirin, C9H8O4, is produced from salicylic acid, C7H6O3, and acetic anhydride, C4H6O3, as shown below.

C7H6O3 + C4H6O3 C9H8O4 + HC2H3O2

(b) How much salicylic acid would be required if only 53% of the salicylic acid is converted to aspirin?

(c) What is the theoretical yield of aspirin if 159 kg of salicylic acid is allowed to react with 149 kg of acetic anhydride?

(d) If the situation described in part (c) produces 163 kg of aspirin, what is the percentage yield?

(a) How much salicylic acid is required to produce 5.0 102 kg of aspirin, assuming that all of the salicylic acid is converted to aspirin? Answer: 380kg

if that clarifies anything....

Answer 1

First of all the MW
C7H6O3 =138
C4H6O3 =102
C9H8O4 =180

a)From the stoichiometry of the reaction:
138 gr of salicylic acid will give in theory 180 gr of aspirin
x kg of of salicylic acid will give in theory 5.0102 kg of aspirin

Thus x= (138/180)* 5.0102 =3.8411 kg.

I don't know why you calculated 380 kg; maybe you are giving us the wromg amount of aspirin

b) The yield is 53% so you have 0.53=3.8411/total =>
total =3.8411/ 0.53 = 7.2473 kg

c)From the stoichiometry of the reaction:
138 gr of salicylic acid react with 102 gr of anhydride
159 kg of salicylic acid react with x kg of anhydride

Thus x=(102/138)*159 =117.5 kg anhydride. You have 149 kg anhydride which means that the limiting reactant is the salicylic acid. So in theory (100% reaction)

138 gr of salicylic acid will give in theory 180 gr of aspirin
159 kg of of salicylic acid will give in theory x kg of aspirin
Thus x= (180/138)*159 =207.4 kg aspirin

d)Yield=(163/207.4)*100% = 78.6 %

Answer 2

What do you want the acid to do? Nothing means anything until you set the circumstances.