| Date | November 2009 | Marks available | 1 | Reference code | 09N.3.sl.TZ0.C3 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain | Question number | C3 | Adapted from | N/A |
Question
Nano-sized ‘test-tubes’ with one open end, can be formed from carbon structures.
Carbon nanotubes can be used as catalysts.
Describe these ‘test-tubes’ with reference to the structures of carbon allotropes.
These tubes are believed to be stronger than steel. Explain the strength of these ‘test-tubes’ on a molecular level.
Suggest two reasons why they are effective heterogeneous catalysts.
State one potential concern associated with the use of carbon nanotubes.
Markscheme
walls have rolled/single sheets of graphite/carbons bonded in hexagons;
ends have half a buckyball (fullerene)/carbons in pentagons (and hexagons);
covalent bonds are very strong;
large surface area;
Do not accept “reactive surface”.
high selectivity related to dimensions of tube;
unknown health effects;
Accept potentially harmful as easily ingested/inhaled.
Accept difficulty of preparing nanotubes in required amounts.
Examiners report
Responses to this question were generally poor perhaps reflecting the unfamiliarity of candidates with the new syllabus content.
Responses to this question were generally poor perhaps reflecting the unfamiliarity of candidates with the new syllabus content.
Responses to this question were generally poor perhaps reflecting the unfamiliarity of candidates with the new syllabus content.
Responses to this question were generally poor perhaps reflecting the unfamiliarity of candidates with the new syllabus content.
