| Date | May 2018 | Marks available | 3 | Reference code | 18M.3.sl.TZ1.3 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe | Question number | 3 | Adapted from | N/A |
Question
Aluminium and high density polyethene (HDPE) are both materials readily found in the kitchen, for example as saucepans and mixing bowls respectively. In these applications it is important that they are impermeable to water.
Both materials are also used in other applications that are more demanding of their physical properties. Carbon nanotubes are often incorporated into their structures to improve certain properties.
Discuss, in terms of its structure, why an aluminium saucepan is impermeable to water.
State the name given to a material composed of two distinct solid phases.
State one physical property of HDPE that will be affected by the incorporation of carbon nanotubes.
Describe how carbon nanotubes are produced by chemical vapour deposition (CVD).
State the property of carbon nanotubes that enables them to form a nematic liquid crystal phase.
Markscheme
«close packed» lattice of metal atoms/ions
no spaces for water molecules to pass though the structure
[2 marks]
composite
[1 mark]
melting point
OR
permeability
OR
density
OR
conductivity
OR
elasticity/stiffness
OR
brittleness/flexibility
OR
«tensile» strength
Accept “colour/transparency”.
[1 mark]
Any three of:
hydrocarbon/carbon-containing gas/compound
mixed with inert gas
heat/high temperature
«transition» metal catalyst
hydrocarbon/carbon compound decomposes to form carbon «nanotubes»
nanotubes form on catalyst surface
Accept “ethanol” or specific hydrocarbons.
Accept “N2”, “H2”, “NH3” or specific inert gases.
Accept temperature or range within 600–800 °C.
Accept specific metals such as Ni, Co or Fe.
[3 marks]
rod shaped molecules
[1 mark]
Examiners report
Syllabus sections
-
17N.3.sl.TZ0.6a:
State equations for the formation of iron nanoparticles and carbon atoms from Fe(CO)5 in the HIPCO process.
- 17N.3.sl.TZ0.6c: Discuss one possible risk associated with the use of nanotechnology.
-
19M.3.hl.TZ2.4e:
Carbon nanotubes are added to metals to increase tensile strength.
Write an equation for the formation of carbon nanotubes from carbon monoxide.
-
18N.3.sl.TZ0.4c:
Arc discharge, consisting of two inert metal electrodes in a liquid solvent, is one method of producing carbon nanotubes (CNTs).
Predict, giving a reason, the electrode at which the solvent cyclohexane, C6H12, will decompose to form CNTs.
-
19M.3.sl.TZ1.6a:
Describe the structure and bonding of a carbon nanotube.
Structure:
Bonding:
-
19M.3.sl.TZ2.4e:
Carbon nanotubes are added to metals to increase tensile strength.
Write an equation for the formation of carbon nanotubes from carbon monoxide.
-
19M.3.hl.TZ1.6b:
Suggest one application for carbon nanotubes.
-
17M.3.sl.TZ1.8b:
Suggest why nanoparticles need to be handled with care.
-
17M.3.sl.TZ1.8a:
State the major advantage that nanoparticles have in these applications.
- 17N.3.sl.TZ0.6b: Outline why the iron nanoparticle catalysts produced by the HIPCO process are more efficient...
-
19N.3.sl.TZ0.3c:
Nanotubes are used to support the active material in nanocatalysts.
Explain why oxygen cannot be used for the chemical vapour deposition (CVD) preparation of carbon nanotubes.
-
18M.3.sl.TZ2.5a:
State the source of carbon for MWCNT produced by arc discharge and by CVD.
-
16N.3.sl.TZ0.5b:
Nanocatalysts play an essential role in the manufacture of industrial chemicals.
(i) Describe the high pressure carbon monoxide (HIPCO) method for the production of carbon nanotubes.
(ii) Outline one benefit of using nanocatalysts compared to traditional catalysts in industry.
-
19M.3.sl.TZ1.6b:
Suggest one application for carbon nanotubes.
-
19M.3.hl.TZ1.6a:
Describe the structure and bonding of a carbon nanotube.
Structure:
Bonding:
-
18M.3.sl.TZ1.3b.ii:
State one physical property of HDPE that will be affected by the incorporation of carbon nanotubes.
- 20N.3.sl.TZ0.4a: Explain these properties of carbon nanotubes.
- 20N.3.hl.TZ0.4a: Explain these properties of carbon nanotubes.
