Question 23M.3.HL.TZ2.4
| Date | May 2023 | Marks available | [Maximum mark: 12] | Reference code | 23M.3.HL.TZ2.4 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Draw, Explain, Give, Identify, Outline, State | Question number | 4 | Adapted from | N/A |
Sections of two forms of polystyrene are shown:
Draw the structural formula of the monomer from which they were formed.
[1]
Accept “−C6H5“ for phenyl group.
Identify, giving one reason, the form with the higher melting point.
[1]
B AND chains «of polymer» can align/pack more closely ✓
Do not accept “stronger intermolecular forces between chains”.
Explain how a substance in the same phase as the reactants can reduce the activation energy and act as a catalyst.
[2]
forms an intermediate/activated complex ✓
«intermediate/activated complex» dissociates to form product «AND catalyst» ✓
Accept correct annotated energy profile for either mark.
Solutions of substituted polystyrenes can form lyotropic liquid crystals. Outline how lyotropic liquid crystals differ from other liquid crystals.
[1]
«lyotropic liquid crystals» exist over a given concentration range AND other liquid crystals exist over a certain temperature range ✓
Expanded polystyrene (EPS) is a useful material.
Explain how polystyrene is converted to EPS.
[2]
volatile hydrocarbon/pentane «incorporated in beads of the polymer» ✓
vaporizes/boils when heated «causing polymer to expand» ✓
Accept names or formulas for M1.
Accept “carbon dioxide” for M1.
State one property of EPS that makes it a useful material.
[1]
«good» thermal/electrical insulator
OR
soft/provides shock resistance
OR
low density
OR
easily moulded/versatile
OR
water resistant
OR
durable ✓
Accept “easy on-site usage”
OR
“environmentally sustainable”
OR
“non-toxic”
OR
«chemically» inert”.
Accept “lightweight” for “low density”.
Nylon-6 is a polymer that can be formed from the monomer:
State the type of polymerization reaction that occurs and the structural characteristic of the monomer that allows this type of polymerization to occur.
Type of polymerization: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Structural characteristic: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[2]
Type of polymerization: condensation ✓
Structural characteristic: two functional groups ✓
Accept “polycondensation” for M1.
Outline why plastics do not break down easily in the environment.
[1]
strong covalent bonds ✓
Accept “close packing of chains”
OR
“hydrophobicity”.
State the RIC number for polyamide plastic (nylon). Use section 30 of the data booklet.
[1]
«RIC» 7 ✓