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Date November 2018 Marks available 1 Reference code 18N.3.hl.TZ0.2
Level HL Paper 3 Time zone TZ0
Command term Deduce Question number 2 Adapted from N/A

Question

One way of classifying materials is based on the type of bonding present.

Caprolactam reacts with water to form compound X, a monomer.

One way of classifying materials is based on the type of bonding present.

One reaction to convert cyclohexanone to caprolactam using concentrated sulfuric acid as a catalyst is shown.

Outline why this type of classification is not entirely satisfactory by using magnesium diboride, MgB2, as an example. Refer to sections 8 and 29 of the data booklet.

[2]
a.

Structures of poly(methyl acrylate), PMA, and Bakelite® are shown.

Suggest, giving reasons, which is the thermoplastic polymer and which is the thermosetting polymer.

[2]
b.

A zeolite is an alternative catalyst for this reaction.

Explain how zeolites act as selective catalysts.

[2]
c.

State the names of the two terminal functional groups in X.

[1]
d.i.

Deduce the repeating unit of the polymer of X.

[1]
d.ii.

Repeating units of several polymers are listed.

The infrared (IR) spectrum of one of these polymers is shown.

Deduce, giving a reason, the name of this polymer and its Resin Identification Code (RIC), using sections 26 and 30 in the data booklet.

[2]
d.iii.

Markscheme

Δ χ  = 0.7 AND average Δ χ = 1.7 ✔

 

bonding between metallic and ionic

OR

more than one type of bonding present

OR

bond type difficult to determine as close to several regions/several types/named bonding types «eg ionic and covalent etc

OR

bond is mostly covalent «based on % covalent scale on diagram»

OR

bond has « 0.7 3.2 × 100 = » 22% ionic character ✔

 

Accept “EN” for “ χ ".

Accept “bond is ionic but close to several regions/several types/other named bonding type(s) (eg covalent, metallic and covalent etc.)”.

Do not accept just “bond is ionic”.

Accept any value for % ionic character in range 15–24% or % covalent character in range 76–85%.

a.

Thermoplastic polymer:

PMA AND «weak» intermolecular/IMFs/London/dispersion/van der Walls/vdW/dipole-dipole forces «between layers/chains»

OR

PMA AND no/few cross-links «between layers/chains» ✔

 

Thermosetting polymer:

Bakelite® AND «strong» covalent bonds «between layers/chains»

OR

Bakelite® AND extensive cross-links «between layers/chains» ✔

 

Do not accept “hydrogen bonding” for M1.

Award [1 max] for correct reasons for both polymer classes even if named polymers are incorrectly classified.

b.

pores/cavities/channels/holes/cage-like structures «in zeolites» have specific shape/size ✔

only reactants «with appropriate size/geometry» fit inside/go through/are activated/can react ✔

c.

amino AND carboxyl ✔

 

Do not accept “carbonyl”, “hydroxyl”.

d.i.

 

Continuation bonds at NH and CO are required for mark.

Ignore any brackets and n.

d.ii.

Name and reason:

PET/PETE AND peak for C=O «at 1700–1750 cm–1» ✔

 

RIC:

1 ✔

 

Accept “PET/PETE AND peak for C–O «at 1050–1410 cm–1»” for M1.

Accept “PET/PETE AND peak(s) for COO” for M1.

Accept name or abbreviation for polymer.

No ECF for M2.

d.iii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.i.
[N/A]
d.ii.
[N/A]
d.iii.

Syllabus sections

Options » A: Materials » A.9 Condensation polymers (HL only)
Options » A: Materials
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