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Properties of compounds:
p-aminophen (4-aminophenol)
C6H7NO
MW = 109.126 g/mol
acetic anhydride
C4H6O3
MW = 102.089 g/mol
Density = 1.082 g/mL (wikipedia)
acetaminophen
C8H9NO2
MW = 151.163 g/mol
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The equation for this reaction is:
(copy and past the equation in google,
and you'll come up with the same equation.)
p-aminophen + acetic anhydride ---> acetaminophen + acetic acid
C6H7NO + C4H6O3 ---> C8H9NO2 + C2H4O2
This is a limiting reagent problem.
When there are competing reactants/reagents,
one of them only allows the reaction to go so far.
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reagent p-aminophen:
mol acetaminophen from p-aminophen =
(0.400 g of C6H7NO)
x (1mol C6H7NO / 109.126 g C6H7NO)
x (1mol acetaminophen / 1mol C6H7NO)
= 0.0036655 mol acetaminophen
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reagent acetic anhydride:
mol acetaminophen from acetic anhydride =
0.450 mL C4H6O3
x (1.082 g C4H6O3/ 1 mL C4H6O3)
x (1 mol C4H6O3 /102.089 g C4H6O3)
x (1 mol acetaminophen / 1mol C4H6O3)
= 0.0047694 mol acetaminophen
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p-aminophen limits the amount
(moles) of acetaminophen produced,
and is the limiting reagent.
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The theoretical yield can be found from the
0.0036655 mol acetaminophen:
0.0036655 mol C8H9NO2
x (151.163 g C8H9NO2 / 1 mol C8H9NO2)
= 0.5540861 g
= 0.554 g acetaminophen (theoretical)
(at 3 sig. figs.)