Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Organic Chemistry
785 practice questions
Topics covered
Practice questions
741–750 of 785
Question 741
3 marks · Easy
Answer and see the solution →Lactic acid, which contains both a carboxylic acid group and an alcohol group in its molecule, can be used to make a biodegradable polyester.
(a)[1 mark]State the two functional groups present in lactic acid that allow it to form a polyester.
(b)[2 marks]Describe how a polyester such as PLA can be formed from lactic acid monomers.
Question 742
1 mark · Easy
Answer and see the solution →State the type of chemical bond in the backbone of PLA that makes it more biodegradable than poly(ethene).
Question 743
3 marks · Easy
Answer and see the solution →Polylactic acid (PLA) is formed by joining multiple lactic acid units.
(a)[1 mark]Draw the displayed formula of lactic acid.
(b)[2 marks]Show (with a labelled diagram or description) how two lactic acid molecules join to form an ester linkage.
Question 744
2 marks · Easy
Answer and see the solution →Polyesters such as polylactic acid (PLA) are more biodegradable than most addition polymers.
Calculate the number of ester linkages in a PLA chain formed from 10 lactic acid monomers. Show your working.
Question 745
2 marks · Easy
Answer and see the solution →Lactic acid () is the monomer for the biodegradable polyester called PLA (polylactic acid).
Draw the displayed (structural) formula for a section of the polylactic acid (PLA) polymer, showing two repeat units joined together.
Question 746
3 marks · Easy
Answer and see the solution →Lactic acid is a monomer that can be used to make the biodegradable polyester polylactic acid (PLA). The data table below shows three monomers, the type of polymerisation they can undergo, and whether the resulting polymer is biodegradable.
Monomer Type of polymerisation Is the polymer biodegradable? Lactic acid Condensation Yes Ethene Addition No Hexanedioic acid and ethane-1,2-diol Condensation Yes Analyse the table and answer the following parts:
(a)[1 mark]State which monomer from the table is used to make PLA.
(b)[1 mark]Based on the table, what type of polymerisation is used to make PLA?
(c)[1 mark]Use the data to give one reason why polylactic acid (PLA) is considered environmentally friendly.
Question 747
2 marks · Normal
Answer and see the solution →State the two types of functional groups present in lactic acid that allow it to form a biodegradable polyester.
Question 748
4 marks · Normal
Answer and see the solution →Biodegradable polyesters such as PLA can be broken down by environmental processes more easily than many other polymers.
(a)[1 mark]Explain what is meant by the term 'ester linkage' in a polyester.
(b)[3 marks]Describe why polyesters with ester linkages are more biodegradable than addition polymers.
Question 749
3 marks · Normal
Answer and see the solution →Lactic acid has the molecular formula . A single lactic acid molecule is used as the monomer for making polylactic acid (PLA).
Calculate the molecular formula of the repeat unit of PLA, given that one molecule of water () is eliminated each time two lactic acid monomers link. Show your working.
Question 750
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).