Aspirin is prepared by reaction of salicylic acid (C7H6O3) with acetic anhydride (C4H6O3)according to the following equation:
C7H6O3Salicylicacid+C4H6O3Aceticanh ydride→C9H8O4Aspirin+CH3COOHAcetica cid

a. How many grams of acetic anhydride are needed to react with 3.07 g of salicylic acid?
b. How many grams of aspirin will result?
c. How many grams of acetic acid are formed as a by-product?

For a: The mass of acetic anhydride reacts is 2.25 grams

For b: The mass of aspirin produced is 3.96 grams

For c: The mass of acetic acid produced is 1.32 grams

Explanation:

To calculate the number of moles, we use the equation:

    .....(1)

Given mass of salicylic acid = 3.07 g

Molar mass of salicylic acid = 138.12 g/mol

Putting values in equation 1, we get:

The chemical equation for the reaction of salicylic acid and acetic anhydride follows:

By Stoichiometry of the reaction:

1 mole of salicylic acid reacts with 1 mole of acetic anhydride

So, 0.022 moles of salicylic acid will react with = of acetic anhydride

Now, calculating the mass of acetic anhydride from equation 1, we get:

Molar mass of acetic anhydride = 102.1 g/mol

Moles of acetic anhydride = 0.022 moles

Putting values in equation 1, we get:

Hence, the mass of acetic anhydride reacts is 2.25 grams

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of aspirin

So, 0.022 moles of salicylic acid will produce = of aspirin

Now, calculating the mass of aspirin from equation 1, we get:

Molar mass of aspirin = 180.16 g/mol

Moles of aspirin = 0.022 moles

Putting values in equation 1, we get:

Hence, the mass of aspirin produced is 3.96 grams

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of acetic acid

So, 0.022 moles of salicylic acid will produce = of acetic acid

Now, calculating the mass of acetic acid from equation 1, we get:

Molar mass of acetic acid = 60 g/mol

Moles of acetic acid = 0.022 moles

Putting values in equation 1, we get:

Hence, the mass of acetic acid produced is 1.32 grams

the dependant variable is spilled water

the independent is the heat