Question

Calculate the theoretical yield of acetaminophen:

and

Percent yield

p-aminophenol: 0.5 g

acetic anhydride: .550mL

Product mass 1.297

Answer 1

P-aminophen + acetic anhydride ---> acetaminophen + acetic acid

Molar mass of p-aminophenol =109.13g/mol

Molar mass of acetic anhydride = 102.1 g/mol

Molar mass of acetaminophen = 151.17 g/mol

Quantity of p-aminophenol = 0.500g

Quantity of acetic anhydride =0.550 ml

Step -1 first Calculate moles of p-aminophenol

Moles of p-aminophenol = mass/molar mass

                                  = 0.500g/(109.13g/mol)

                                  = 0.00458 mol

Step -2 Calculate moles of acetic anhydride

Volume of acetic anhydride =0.550 ml

Density = 1.082 g/mL

Mass of acetic anhydride = V x D = 0.550 ml x 1.082 g/mL = 0.5951 g

Moles of acetic anhydride = mass/molar mass

                                         = 0.5951g/(102.9g/mol)

                                         = 0.00578 mol

Step -3 Find the limiting reagent

The limiting agent has due to following properties:

1. It completely reacted in the reaction.
2. It determines the amount of the product in mole.

P-aminophen limits the amount of acetaminophen produced, so it is the limiting reagent.

Step -4 Calculate moles of acetaminophen

1 mol of P-aminophen produces 1 mol of acetaminophen

So, 0.00458 mol of P-aminophen produces 0.00458 mol of acetaminophen

Step -5 Calculate theoretical yield of acetaminophen

Theoretical Yield = moles of acetaminophen x molar mass of acetaminophen

                       = 0.00458 mol x 151.17g/mol

                         = 0.692g of acetaminophen

Percent Yield = (Actual yield / Theoretical yield) x 100 %

Actual yield is always less than Theoretical yield