A polymer chemist studies two reactions, P and Q. The table gives information about the starting molecules and one repeating unit of each polymer.
| Reaction | Starting molecule(s) | Functional group information | Formula of one repeating unit |
|---|---|---|---|
| P | One molecule with formula C4H8\text{C}_4\text{H}_8C4H8 | Contains a C=C\text{C}=\text{C}C=C bond | C4H8\text{C}_4\text{H}_8C4H8 |
| Q | Molecule X, C4H10O2\text{C}_4\text{H}_{10}\text{O}_2C4H10O2, and molecule Y, C2H2O4\text{C}_2\text{H}_2\text{O}_4C2H2O4 | X has an OH\text{OH}OH group at each end; Y has a COOH\text{COOH}COOH group at each end | C6H8O4\text{C}_6\text{H}_8\text{O}_4C6H8O4 |
A chemist considers two candidates to replace X in reaction Q.
| Candidate | Structure |
|---|---|
| A | HO-CH2-CH2-OH\text{HO-CH}_2\text{-CH}_2\text{-OH}HO-CH2-CH2-OH |
| B | CH3-CH2-OH\text{CH}_3\text{-CH}_2\text{-OH}CH3-CH2-OH |
Explain, using the data, why one repeating unit from reaction P contains the same atoms as its monomer but one repeating unit from reaction Q does not. Use the formulae to determine the number of water molecules equivalent to the atoms missing from one repeating unit of Q.
Which candidate could replace X while allowing reaction Q to form a long polymer chain? Justify your choice using the structures.
94 exam-style questions on AQA GCSE Chemistry 7.3 Synthetic and naturally occurring polymers, covering 7.3.1 Addition polymerisation, 7.3.2 Condensation polymerisation, 7.3.3 Amino acids, and 7.3.4 DNA (deoxyribonucleic acid) and other naturally occurring polymers. Each one has a worked solution and a mark scheme showing where the marks go.