Synthetic and Naturally Occurring Polymers

1. Describe what happens in addition polymerisation reactions.

Answer: Many small molecules (monomers) join together to form very large molecules (polymers).


2. Name the polymer made from butene.

Answer: poly(butene)


3. Name the monomer used to make poly(propene).

Answer: propene


4. Name the monomers needed to make a polyester.

Answer: diol and a dicarboxylic acid


5. What do amino acids make when they polymerise?

Answer: polypeptide


6. What is a protein made from?

Answer: Different amino acids in the same polymer chain.


7. What does DNA stand for?

Answer: deoxyribonucleic acid


8. Give three examples of natural polymers that are important to life.

Answer: proteins, starch and cellulose


9. What is the shape of DNA?

Answer: double helix


10. Poly(ethene) is an addition polymer.

a) Name the monomer used to make poly(ethene).

Answer: ethene


b) Draw the repeating unit of poly(ethene).

Answer: 


c) Explain why the repeating unit of the polymer will have the same relative formula mass as the monomer.

Answer: The repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction.


11. Polyesters are often used to make fibres and fabrics. They are made from two different monomers.

a) Ethane-diol is one of these monomers. It has the structural formula shown in the figure below. Give the molecular formula of ethane-diol.


Answer: C2H6O2


b) Hexandioic acid is the second monomer that is used. Give its functional group and homologous series.

Answer: –COOH , carboxylic acid


c) The polyester can be represented in a block diagram as shown in the figure below. Draw the block structures for the two monomers.


Answer: 


d) Give the formula of the second product of this polymerisation reaction.

Answer: H2O


12. Amino acids are the important building blocks of life. Glycine is the simplest amino acid. The figure below shows the displayed formula of glycine.


a) Circle the two functional groups on the displayed formula of glycine.

Answer: 


b) Glycine can react with itself to make a polymer. Write a symbol equation to show this reaction.

Answer: 


c) Name the type of polymerisation that happens when glycine reacts with itself. Describe this type of polymerisation.

Answer: Condensation polymerisation as there are two products, the polymer (polypeptide) and a small molecule (water).


d) Identify the two products of this reaction.

Answer: polypeptide and water


13. DNA is a natural polymer found in the nuclei of cells. Use the figure below and your own knowledge to describe the shape, structure and bonding in a molecule of DNA.


Answer: The atoms are held by covalent bonds made of shared pairs of electrons. The DNA molecule is a giant molecule (macromolecule) made of many atoms. Each polymer chain is made from different monomers (nucleotides). The DNA molecule is two polymer chains, which are coiled together to make a double helix.


14. Synthetic polymers can be made by addition polymerisation or condensation polymerisation. Compare these types of polymerisation. You should include examples of each type in your answer.

Answer: Both forms of polymerisation make a very large molecule. Addition polymerisation uses one monomer but condensation polymerisation uses two monomers. Addition polymerisation uses a monomer that is unsaturated (contains C=C). Condensation polymerisation monomers do not have C=C. Addition polymerisation has only one product but condensation polymerisation has two products. Examples of addition polymers include poly(ethene), poly(propene), PVC. Examples of condensation polymers include polyamide, nylon, polyester.


15. Poly(ethene) is a widely manufactured polymer. The pie charts in the figure below show the uses of low density polyethene (LDPE) and high density polyethene (HDPE).


a) Calculate the percentage use of film for LDPE.

Answer: 100 - (8 + 5 + 4 + 7) = 76 %


b) Calculate the amount of other uses for HDPE. Give your answer as a fraction.

Answer: 5/100 = 1/20


c) There was 18.7 million tonnes of LDPE made in the world in 2014. Calculate the mass used in injection moulding.

Answer: 18.7 × 0.05 = 0.935 million tonnes