Question

How would I find the theoretical and percent yield of a Fischer esterification? I used 1.5 mL of 1-pentanol (MW: 88 g/mol ; Density= 0.811 g/mL) and 3 mL of glacial acetic acid (MW: 60 g/mol ; Density= 1.06 g/mL). This gave the formation of pentyl acetate (MW: 130.19 g/mol). The crude product was 1.006 g and the distillation product was 0.19 g

Answer 1

1 mol 1-pentanol requires 1 mol acetic acid to produce 1 mol pentyl acetate (n-amyl acetate) having banana odor.

moles calculation:

density = mass / volume ==> mass = density x volume

moles = mass of substance / MW of substance

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moles = mass of alcohol / MW of alcohol

mass of pentanol = 1.5 mL x 0.811 g /mL = 1.2165 g

moles pentanol = 1.2165 g / 88 g/mol = 0.0138 mol

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moles = mass of acid / MW of acid

mass of acid = 3 mL x 1.06 g /mL = 3.18 g

moles acid = 3.18 g / 60 g/mol = 0.053 mol

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clearly acid is in excess, hence alcohol is limiting reactant

now 0.0138 mol alcohol reacts only with 0.0138 mol acetic acid and produces 0.0138 mol ester

convert mol ester to mass ester = theoretical yield

mass ester (Theoretical yield) = 0.0138 mol x 130.19 g/mol = 1.797 g

Theoretical yield = 1.797 g

percent yield = (actual yield / theoretical yield) x 100% = (0.19 g / 1.797 g) x 100% = 10.6%

percent yield = 10.6% ---------------- crude product is not considered as pure, distilled one is pure

Hope this helped you!

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