Addition polymerisation

4 marks · Normal

The table below shows information about three addition polymers and the number of carbon atoms in their repeat units.

Polymer	Monomer	Number of C atoms in repeat unit
Poly(ethene)	ethene	2
Poly(propene)	propene	3
Poly(chloroethene)	chloroethene	2

(a)

Which polymer in the table has a repeat unit containing the highest number of carbon atoms? Explain your answer.

[1 mark]

(b)

Draw the repeat unit for poly(propene).

[2 marks]

(c)

Name the monomer used to make poly(chloroethene).

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) Poly(propene) because its repeat unit contains 3 carbon atoms. · must show Identifies poly(propene), Explains answer using data from table

(b) Displayed formula of —CH2—CH(CH3)— · must show Repeat unit drawing must have backbone —CH2—CH—, with a —CH3 attached to one of the carbons, Brackets and n subscript preferred

Also accept: Accept displayed or line formula for poly(propene)'s repeat unit

Common mistakes: Incorrectly drawing repeat unit with a double bond

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Identifies poly(propene) and refers to 3 carbon atoms in repeat unit as evidence

M1 (b) · 1 mark · Draws correct backbone connections (—CH2—CH—)

A1 (b) · 1 mark · Shows —CH3 as a side group and brackets (with n subscript if included)

B2 (c) · 1 mark · Gives correct monomer name for poly(chloroethene)

Worked solution

a) Poly(propene) has 3 carbon atoms in its repeat unit (see the table), so it has the highest.

b) The repeat unit for poly(propene) is:

c) The monomer for poly(chloroethene) is chloroethene (or vinyl chloride).