Practical: making and testing the smell of some esters in the lab
2 marks · NormalState two reasons why sodium carbonate solution is added at the end of the ester preparation process.
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Must show: neutralise excess acid, making ester smell easier
Also accept: To neutralise/remove excess acid; to help detect/smell ester better; To remove acidic smell so the ester smell can be detected
Common mistakes: thinking it increases yield; saying 'to purify the ester' only
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Marking points
B1 · 1 mark · States that sodium carbonate neutralises excess acid in the mixture.
B2 · 1 mark · States that it allows the ester’s smell to be detected more easily/removes acid smell.
Worked solution
Sodium carbonate is added to neutralise any remaining acid and to make it easier to detect the smell of the ester by removing the acidic odour.