DP Chemistry (first assessment 2025)
Question 23M.2.HL.TZ2.5a
Date | May 2023 | Marks available | [Maximum mark: 4] | Reference code | 23M.2.HL.TZ2.5a |
Level | HL | Paper | 2 | Time zone | TZ2 |
Command term | Explain, Identify, State | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 4]
23M.2.HL.TZ2.5a
(a)
The unit cell of lead (II) sulfide is shown:
(a.i)
State the coordination number of the lead (II) ion.
[1]
Markscheme
6 ✓

(a.ii)
There are 14 sulfide ions shown in the diagram. Explain why the unit cell is only considered to contain 4 sulfide ions.
[2]
Markscheme
6 on faces «shared between two unit cells» so 6x½ = 3 ✓
8 on corners «shared between eight unit cells» so 8x⅛ = 1 ✓

(a.iii)
Identify one technique that could be used to determine the structure of lead (II) sulfide.
[1]
Markscheme
X-ray crystallography/diffraction ✓
Accept “electron/neutron diffraction”.
