Synthetic polymers (Edexcel IGCSE Science (Double Award): Chemistry)

Poly(chloroethene) is a polymer.

It is made from its monomer, chloroethene.

Chloroethene has the percentage composition by mass

C = 38.4%      H = 4.8%      Cl = 56.8%

Show, by calculation, that the empirical formula of chloroethene is C₂H₃Cl

The molecular formula of chloroethene is also C₂H₃Cl

Chloroethene can be prepared by a two‐stage process.

In stage 1, ethene reacts with chlorine in the presence of an iron(III) chloride catalyst to form dichloromethane.

The reaction is exothermic.

C₂H₄ + Cl₂ → C₂H₄Cl₂

i) Give the formula of iron(III) chloride.

(1)

ii) State the purpose of using a catalyst.

(1)

iii) State the meaning of the term exothermic.

(1)

iv) What type of reaction occurs in stage 1 between ethene and chlorine?

(1)

v) In stage 2, dichloroethane decomposes into chloroethene and hydrogen chloride. Give a chemical equation for this reaction.

(1)

i) Draw the displayed formula of

• chloroethene

• the repeat unit of poly(chloroethene)

(3)

ii) Draw a dot‐and‐cross diagram to represent a molecule of chloroethene. Show only the outer electrons of each atom.

(2)

Why do addition polymers not biodegrade easily?

This question is about alkenes and polymers.

Ethene (C₂H₄) can be represented by different types of formula.

i) Complete the table by giving the missing information.

(2)

ii) Ethene is a member of the homologous series of alkenes. All members of the same homologous series have the same general formula. Give two other characteristics of a homologous series.

(2)

1. ............................................................................
2. ............................................................................

Ethene is used to make poly(ethene).

 i) State the type of polymerisation used to form poly(ethene).

(1)

ii) Complete the equation for the polymerisation of ethene.

(2)

iii) Poly(ethene) is used to make plastic bags. Corn starch from plants can also be used to make polymers for plastic bags. The table gives some information about poly(ethene) and polymers made from corn starch.

Use the information in the table and your knowledge to discuss the advantages and disadvantages of using poly(ethene) to make plastic bags.

(5)

The diagram shows the repeat unit of another polymer.

Draw the displayed formula of the monomer used to make this polymer.

Which of the following statements about polymers is NOT correct?

The structure of a polymer is shown below.

What is the correct monomer?

Which statement is the correct description of a polymer?