Making a polyester

2 marks · Hard

State the names of the two functional groups present in the monomers that react together to form a polyester. For each group, state the name of the organic compound type it is found on (use "diol" or "dicarboxylic acid").

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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Hydroxyl (–OH) group on a diol and carboxyl (–COOH) group on a dicarboxylic acid.

Also accept: –OH group on a diol and –COOH group on a dicarboxylic acid; Alcohol group on a diol and carboxylic acid group on a dicarboxylic acid

Common mistakes: Confusing with alkene group; Not stating compound type (diol or dicarboxylic acid)

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Marking points

B1 · 1 mark · States (hydroxyl/–OH/alcohol) group on a diol (or equivalent)

B2 · 1 mark · States (carboxyl/–COOH/carboxylic acid) group on a dicarboxylic acid (or equivalent)

Worked solution

Polyesters are formed when a diol and a dicarboxylic acid react together.

A diol contains two hydroxyl (–OH) groups, and a dicarboxylic acid contains two carboxyl (–COOH) groups.

Answer: Hydroxyl (–OH) group on a diol, and carboxyl (–COOH) group on a dicarboxylic acid.