DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ2.4d
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ2.4d |
| Level | hl | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | d | Adapted from | N/A |
d.
[Maximum mark: 2]
19M.3.hl.TZ2.4d
Metals are extracted from their ores by several methods, including electrolysis and reduction with carbon.
(d)
Outline how alloys conduct electricity and why they are often harder than pure metals.
Conduct electricity:
Harder than pure metals:
[2]
Markscheme
Conduct electricity:
«delocalized/valence» electrons free to move «under potential difference» [✔]
Harder than pure metals:
atoms/ions of different sizes prevent layers «of atoms/ions» from sliding over one another [✔]
Examiners report
Most candidates were awarded one mark for how alloys conduct electricity. Some struggled with describing why they are harder than pure metals.
