Uses of esters
3 marks · NormalEsters are widely used in everyday products.
State one use of esters as a flavouring in the food industry.
Perfume manufacturers often use mixtures including esters.
State why esters are useful in perfumes.
A chemist designs an artificial pear flavour. Estimate how many individual esters, from the following list, could be combined for this purpose: ethyl ethanoate, methyl butanoate, propyl ethanoate, and butyl methanoate.
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(a) Used to give fruity flavours to foods and drinks (e.g. as a banana or pear flavouring)
(b.i) They are volatile (easily evaporate) and have pleasant/sweet/fruity smells
(c) 4
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Marking points
B1 (a) · 1 mark · Identifies a use of esters as a flavouring in food or drink
B1 (b(i)) · 1 mark · States that esters are volatile and/or have pleasant/fruity smell (either point sufficient)
B1 (c) · 1 mark · Correctly states 4 as the number of possible separate esters from the given list
Worked solution
(a) Esters are used as flavourings in foods and drinks. For example, ethyl butanoate gives a pineapple flavour.
(b) Esters are useful in perfumes because they are volatile (evaporate easily) and have pleasant, fruity smells.
(c) There are four esters listed: ethyl ethanoate, methyl butanoate, propyl ethanoate, and butyl methanoate. Any or all could be combined for artificial pear flavour. Answer: 4