Esters
5 marks · EasyThe reaction between propanoic acid and methanol produces methyl propanoate and water.
Write a balanced equation (using formulae) for the reaction of methanol and propanoic acid to form an ester.
Name the ester formed in this reaction.
Give one reason why esters are added to food and drink products.
If 0.1 mol of propanoic acid and 0.1 mol of methanol are reacted, calculate the maximum amount (in mol) of ester that can be produced.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) CH3CH2COOH + CH3OH → CH3CH2COOCH3 + H2O
(b) methyl propanoate
(c) To provide a sweet/fruity flavour or pleasant smell
(d) 0.1 mol
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Writes correct reactants (propanoic acid and methanol) and products (ester and water)
A1 (a) · 1 mark · Correctly balances the equation and uses correct formulae
B1 (b) · 1 mark · Gives correct name: methyl propanoate
B2 (c) · 1 mark · States correct reason: provides flavour/smell
A2 (d) · 1 mark · Correctly calculates 0.1 mol ester
Worked solution
(a) CH3CH2COOH + CH3OH → CH3CH2COOCH3 + H2O
(b) The ester formed is methyl propanoate.
(c) Esters are added as flavourings because they give sweet/fruity flavours or pleasant smells.
(d) Since both reactants are present in 0.1 mol and combine 1:1, maximum possible ester formed is 0.1 mol.