Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Biodegradable polyesters
18 practice questions
Practice questions
11–18 of 18
Question 11
4 marks · Normal
Answer and see the solution →The table shows the time taken for different types of polymers to degrade in soil:
Degradation times of polymers in soil Polymer Degradation time (months) PLA (polylactic acid) 12 Poly(ethene) 400 Poly(ester) 18 Poly(propene) 350 Use the data to answer the questions.
(a)[1 mark]Which polymer is the most biodegradable? Give the evidence from the table.
(b)[3 marks]Explain, using your knowledge of chemical structure, why PLA degrades faster than poly(ethene) or poly(propene).
Question 12
1 mark · Normal
Answer and check →Which of the following shows the correct displayed formula for the repeat unit of polylactic acid (PLA)?
- A.—[O—CH(CH3)—CO]—
- B.—[CH2—CH(OH)—CO]—
- C.—[O—CH2—CO]—
- D.—[CH(OH)—CH3—COO]—
Question 13
2 marks · Normal
Answer and see the solution →Describe how polylactic acid (PLA) is produced from its monomer, lactic acid.
Question 14
4 marks · Normal
Answer and see the solution →Polyesters are condensation polymers that are more biodegradable than many addition polymers.
(a)[1 mark]State what is meant by a condensation polymerisation reaction.
(b)[3 marks]With reference to chemical bonding, explain why polyesters can be biodegraded more easily than addition polymers.
Question 15
3 marks · Normal
Answer and see the solution →Lactic acid has the formula . When making a biodegradable polyester such as polylactic acid (PLA), lactic acid monomers react with each other to form a long polymer chain.
Explain, using your knowledge of its structure, how lactic acid can form a biodegradable polyester like PLA from a single type of monomer.
Question 16
2 marks · Hard
Answer and see the solution →Describe how the biodegradable polyester polylactic acid (PLA) can be made from its monomer, lactic acid. In your answer, state the name of both the process and the type of chemical reaction involved.
Question 17
5 marks · Hard
Answer and see the solution →Polyesters, such as polylactic acid (PLA), often biodegrade more rapidly than addition polymers like poly(ethene).
Answer the following questions about their biodegradability.
(a)[1 mark]Explain what is meant by 'biodegradable polyester'.
(b)[1 mark]State what is meant by an 'ester linkage' in the context of polyester structure.
(c)[3 marks]Compare the biodegradability of polyesters (such as PLA) and addition polymers (such as poly(ethene)).
Explain why polyesters with ester linkages are more biodegradable, referring to the chemical structure and environmental breakdown processes.
Question 18
2 marks · Hard
Answer and see the solution →Lactic acid is the monomer for polylactic acid (PLA). What is the displayed (structural) formula for the part of a PLA chain that is actually repeated in the polymer? Describe or draw the repeat unit of PLA, indicating the ester linkage.