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.

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

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

A zeolite is an alternative catalyst for this reaction.

Explain how zeolites act as selective catalysts.

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

Deduce the repeating unit of the polymer of X.

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.

$\mathrm{\Delta }\chi$ = 0.7 AND average $\mathrm{\Delta }\chi$ = 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 « $\frac{0.7}{3.2}\times 100=$» 22% ionic character ✔

Accept “EN” for “$\chi$".

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%.

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.

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 ✔

amino AND carboxyl ✔

Do not accept “carbonyl”, “hydroxyl”.

Continuation bonds at NH and CO are required for mark.

Ignore any brackets and n.

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.