Esters

Question 1

what are esters?

Answer 1

a family of organic molecules which form when a carboxylic acid and alcohol join together by losing a water molecule

Question 2

when drawing esters where does the ester functional group (-COO-) go?

Answer 2

• it sits between two carbon chains, joining them together
• it doesn’t matter what the other carbon chains look like, so they are represented by question marks in a diagram

Question 3

when is the ester formed when ethanoic acid and ethanol react?

Answer 3

ethyl ethanoate

Question 4

what is the reaction between ethanoic acid and ethanol called?

Answer 4

condensation - because of the production of water vapour

(sometimes it is called esterification because it makes an ester)

Question 5

how to make an ester

Answer 5

to prepare an ester, you would:

1. mix the carboxylic acid and alcohol together
2. add a few drops of concentration sulfuric acid - this acts as a catalyst for the reaction
3. warm it for a whole
4. tip the mixture into sodium carbonate solution - this neutralises the sulfuric acid catalyst, which is otherwise really corrosive (the reaction produces carbon dioxide so you wait until the fizzing has stopped)

Question 6

what are esters used for and why?

Answer 6

esters are volatile compounds with distinctive smells that make them suitable for use in food flavourings and perfumes

Question 7

how do you choose the correct carboxylic acid and alcohol to make a particular ester?

Answer 7

you draw it and then split it down the middle where the oxygen atom is in line with the carbon chain