Polyesters are a type of condensation polymer. They can be made by reacting a dicarboxylic acid with a diol.
Figure 1 shows a simplified representation of the repeating unit of a polyester chain.

Give the chemical formula of the other substance produced in this condensation polymerisation reaction.
Practise Edexcel GCSE Chemistry Polymers with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.