Question

Identify R and R' in Equation 1 when the ester, aspirin, is made from salicylic acid and acetic acid. (Equation 1) Calculate the theoretical yield of aspirin to be obtained in this experiment, strating with 2.0g of salicylic acid and 5.0mL of acetic anhydride (density 1.08 g/mL).

Answer 1

Answer:

in theoretical yield are obtained  2.61 g of aspirin from 2.0 g of salicylic acid and 5 mL of acetic anhydride

Explanation:

Aspirin (C9H8O4)

∴ mm C9H8O4 = 180 g/mol

salicylic acid (C7H6O3)

∴ mm C7H6O3 = 138 g/mol

acetic anhydride (C4H6O3)

∴ mm C4H6O3 = 102 g/mol

acetic acid (C2H4O2)

∴ mm C2H4O2 = 60 g/mol

reaction:

• C7H6O3 + C4H6O3 → C9H8O4 + C2H4O2

∴ g C7H6O3 = 2.0 g

∴ g C4H6O3 = (5.0 mL)(1.08 g/mL) = 5.4 g

limit reagent (L.R):

∴ n C7H6O3 = (2 g)(mol/138 g) = 0.0145 mol C7H6O3 (L.R)

∴ n C4H6O3 = (5.4 g)(mol/102 g) = 0.053 mol C4H6O3 (E.R)

theoretical yield:

Amount of product predicted by balanced equation when all limit reagent reacts

⇒ n C9H8O4 = (0.0145 mol C7H6O3)(mol C9H8O4/mol C7H6O3) = 0.0145 mol C9H8O4

⇒ g C9H8O4 = (0.0145 mol)(180 g/mol) = 2.61 g C9H8O4