Question

Aspirin can be prepared from salicylic acid ( C 7 H 6 O 3 CX7HX6OX3), which has a molar mass of 138.12 g/mol, and acetic anhydride ( C 4 H 6 O 3 CX4HX6OX3), which has a molar mass of 102.04 g/mol. The density of acetic anhydride is 1.082 g/mL. C 7 H 6 O 3 + C 4 H 6 O 3 ⟶ C 9 H 8 O 4 + C 2 H 3 O 2 CX7HX6OX3+CX4HX6OX3⟶CX9HX8OX4+CX2HX3OX2 What is the theoretical yield, in grams, of aspirin ( C 9 H 8 O 4 CX9HX8OX4), which has a molar mass of 180.15 g/mol, possible when reacting 3.20 g of salicylic acid with 3.71 mL of acetic anhydride? Type answer:

Answer 1

Answer: The theoretical yield of aspirin is 4.14 g

Step-by-step explanation:

To calculate the moles :

`\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}`
`\text{Moles of salicylic acid}=(3.20g)/(138.12g/mol)=0.023moles`

mass of acetic anhydride =
`density* volume =1.082g/ml* 3.71ml=4.01g`

`\text{Moles of acetic anhydride}=(4.01g)/(102.04g/mol)=0.039moles`

`C_9H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+C_2H_3O_2`

According to stoichiometry :

1 mole of salycylic acid require 1 mole of acetic anhydride

Thus 0.023 moles of salycylic acid require=
`(1)/(1)* 0.023=0.023moles` of acetic anhydride

Thus salycylic acid is the limiting reagent as it limits the formation of product and acetic anhydride is the excess reagent.

As 1 mole of salycylic give = 1 mole of aspirin

Thus 0.023 moles of salycylic acid give =
`(1)/(1)* 0.023=0.023moles` of aspirin

Mass of aspirin =
`moles* {\text {Molar mass}}=0.023moles* 180.15g/mol=4.14g`

Thus theoretical yield of aspirin is 4.14 g