Practical: making and testing the smell of some esters in the lab
4 marks · NormalA chemistry student mixes methanol and butanoic acid to make an ester using the laboratory method.
Name the ester formed.
Briefly outline the apparatus set-up used for heating the reaction mixture safely.
How would you test for the presence of the ester after the reaction is complete?
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) methyl butanoate
(b) Set up a boiling tube with the reagents, place it in a beaker of hot water (around 80°C) and heat using a Bunsen burner beneath the water bath, ensuring no naked flame is in direct contact with the flammable organic mixture. · must show reaction vessel is immersed in water, heated indirectly, no direct flame
(c) By gently wafting the odour to detect a fruity or sweet smell. · must show wafting, smell
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly names ester: methyl butanoate.
M1 (b) · 1 mark · Mentions use of a water bath or indirect heating.
B2 (b) · 1 mark · States that there must be no direct contact with flame / contents are flammable.
B3 (c) · 1 mark · Tests for ester by wafting odour to detect sweet/fruity smell.
Worked solution
a) The ester is methyl butanoate.
b) The boiling tube containing the mixture is placed in a beaker of hot water heated by a Bunsen burner or other means, not directly on the flame, to avoid igniting flammable vapours.
c) The presence of the ester can be tested by wafting the smell and noting a sweet, fruity odour.