Esters, condensation polymers and proteins
Watch the whole lecture free
Make a free account to watch every lecture to the end: 1 worked example, 4 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
That was the teaching part. The rest of this lecture is free with an account: 1 worked example, 4 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
No password needed now: we email you a link to set one. Already have an account? Sign in, then come back to this page.
The teaching part (1 min) is free to watch. A free account opens the whole lecture: 1 worked example, 4 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Pineapple, polyester and protein
- Esters
- The equation
- Naming esters
Read the transcript of the teaching part
Last time
Before we start: last time, in Condensation polymers and proteins, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Pineapple, polyester and protein
The smell of pineapple, the fabric of a fleece jacket, and the muscle in your arm. They look unrelated, but all three are held together by the same kind of reaction: two molecules join and give off water. This is condensation, and it makes esters, polyesters, nylon and proteins.
Esters
An ester is made when a carboxylic acid reacts with an alcohol. Water is also formed. A little concentrated sulfuric acid is added as a catalyst, and the mixture is warmed. The reaction is reversible, so we show it with the double arrow.
The equation
CH 3 COOH plus C 2 H 5 OH gives CH 3 COOC 2 H 5 plus H 2 O. The ester linkage is COO, between the carbon chain of the acid and the alkyl group of the alcohol. The ester is ethyl ethanoate. The Mr: 60 plus 46 equals 88 plus 18, so 106 on both sides.
Naming esters
The first word comes from the alcohol: methanol gives methyl, ethanol gives ethyl. The second word comes from the acid: ethanoic acid gives ethanoate. So methanol and ethanoic acid make methyl ethanoate, CH 3 COOCH 3.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Condensation polymers · Esters and esterification · Proteins · Condensation and natural polymers · Esters.
The whole chapter: Organic Chemistry, Organic Chemistry.
Chapter 11: Organic chemistry
- Homologous series, naming and saturation 5 min
- Petroleum and cracking 5 min
- Reactions of alkanes and alkenes 5 min
- Addition polymers 6 min
- Ethanol: manufacture, combustion and oxidation 6 min
- Esters, condensation polymers and proteins 6 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.