Question 23M.3.SL.TZ1.3
| Date | May 2023 | Marks available | [Maximum mark: 13] | Reference code | 23M.3.SL.TZ1.3 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Calculate, Deduce, Discuss, Explain, Identify, Outline, Suggest, Write | Question number | 3 | Adapted from | N/A |
New materials have brought many benefits to society but come with associated risks.
High-pressure carbon monoxide disproportionation (HiPco) produces carbon atoms that react with nano catalysts to produce carbon nanotubes.
Write the equation for the disproportionation of carbon monoxide to produce carbon atoms.
[1]
2CO(g) → C(s) + CO2(g) ✓
Accept reversible arrows.
Calculate the percent atom economy of producing carbon using this method. Use section 1 of the data booklet.
[1]
«100 × 12.01 / 2 × (12.01+16.00) = » 21.44 % ✓
Outline how a metal functions as a heterogeneous catalyst.
[2]
«gaseous» reactants adsorb onto «metal» surface
OR
catalyst provides surface for reaction to occur ✓
weakens «reactant» bonds
OR
products desorb ✓
Accept lowers activation energy for M2.
Explain whether the production of carbon nanotubes using HiPco is a bottom up or top down nanotechnology technique.
[1]
bottom up AND molecular assembly «rather than decomposition» ✓
Suggest one health risk of using nanoparticles.
[1]
Any one of:
more easily airborne/inhaled ✓
have similar dimensions as biological molecules/interfere with biochemical reactions ✓
easily absorbed into body ✓
may cross cell membranes ✓
large surface area could increase toxicity ✓
human defence system not effective with small size ✓
Do not accept just large surface area OR toxic/increased toxicity.
Kevlar® is a recyclable polyamide polymer and a liquid crystal. One repeating unit of the polyamide is shown.
Outline what is meant by a liquid crystal.
[1]
fluids with «some» properties that are anisotropic/depend on molecular orientation «relative to a fixed axis» ✓
Do not accept general references to a mesophase.
Some liquid crystal displays (LCD) use liquid crystals between two polarizing filters. The display appears black until a small voltage is applied. Outline how the liquid crystals allow polarized light to pass through the filters.
[2]
polar «molecules» ✓
change orientation upon application of electric field
OR
«in some orientations» molecules rotate plane of polarization «of polarized light» ✓
Identify the resin identification code (RIC) that applies to Kevlar®. Use section 30 of the data booklet.
[1]
7 ✓
The IR spectrum of Kevlar® is shown.
[Source: A. Campopiano, A. Cannizzaro, A. Olori, S. Boccanera. Study of a selection of man-made organic fibres.
Prevention Today, vol.5, n.1/2, 33–49. Editorial Office: ISPESL-Department of Organization Processes. (The law
of 30 July 2010, n. 122 attributed to INAIL the functions performed in the past by ISPESL).]
Deduce the peak in the Kevlar® IR spectrum which would not be found in compounds with any other RIC code. Use Sections 26 and 30 of the data booklet.
[1]
3300 to 3500 ✓
Accept amine/amide/N-H bond.
Discuss one environmental advantage and one disadvantage of using plastics.
Advantage: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Disadvantage: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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[2]
Advantage:
Any one of:
long life span/easily reused ✓
less energy required for manufacturing «due to long life span» ✓
light weight for construction of vehicles ✓
less energy required by vehicles «due to high strength to density ratio» ✓
can be easily moulded into shape ✓
less material/waste «as high strength to density ratio/easily moulded» ✓
Disadvantage:
Any one of:
non-renewable ✓
much plastic ends up in ocean ✓
hazard to wildlife ✓
takes long time to decompose ✓
can contain dioxin/health hazard ✓
toxic fumes when burned ✓
Accept do not produce methane in landfills as an advantage.
Do not accept cost arguments for either.
Accept other environmental considerations.
Do not accept converse of the advantage as the disadvantage:
e.g. long life span
and
takes too long to decompose