Esters Cambridge IGCSE Chemistry (9–1) revision
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In plain words
The smell of pear drops, bananas and pineapple sweets is the smell of esters. They are made by joining an alcohol to a carboxylic acid. Because they smell pleasant and evaporate easily, they go into perfumes and food flavourings.
Three things to know
- An ester is made from an alcohol and a carboxylic acid, with an acid catalyst. Water is the other product.
- The name comes from both: the alcohol gives the first word (-yl) and the acid gives the second (-oate). Ethanol and ethanoic acid give ethyl ethanoate, CH₃COOCH₂CH₃.
- Esters are volatile (they evaporate easily) and have sweet, fruity smells, so they are used in perfumes and flavourings.
Worked example
Name the ester made from propanol and ethanoic acid.
- The alcohol gives the first word: propanol becomes propyl.
- The acid gives the second word: ethanoic acid becomes ethanoate.
- Propyl ethanoate.
Tips and tricks
- Alcohol first, acid second: ethanol + methanoic acid makes ethyl methanoate.
- Don't forget the water. Every ester equation ends "+ H₂O".
It lands in your notebook with its questions as flashcards.
Esters: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What are esters made from?
They join, with the loss of water.
What is a typical property of esters?
That is why they are used in flavourings.
What is the other product when an ester is made?
The alcohol and the acid join, and water is left over.
What are esters used for?
They smell pleasant and evaporate easily.
What is CH₃COOCH₂CH₃ called?
It is made from ethanol and ethanoic acid.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 6 marks. Write your answers on paper, then check them.
Esters
Cambridge IGCSE Chemistry (9–1) 0971 · 6 marks · papermunch.org
Name ______________________________ Date ______________
Name the ester made from ethanol and ethanoic acid, and the other product of the reaction.[2]
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Ethyl ethanoate. Water.
Give two uses of esters, and the property that makes them suitable.[2]
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Perfumes and food flavourings: they have pleasant, fruity smells (and are volatile).
Name the ester made from methanol and ethanoic acid.[2]
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Methyl ethanoate.
Answers: Esters
- 1. Ethyl ethanoate. Water.
- 2. Perfumes and food flavourings: they have pleasant, fruity smells (and are volatile).
- 3. Methyl ethanoate.