DP Chemistry (last assessment 2024)
Question 18N.3.hl.TZ0.d.ii
| Date | November 2018 | Marks available | [Maximum mark: 1] | Reference code | 18N.3.hl.TZ0.d.ii |
| Level | hl | Paper | 3 | Time zone | TZ0 |
| Command term | Outline | Question number | d.ii | Adapted from | N/A |
d.ii.
[Maximum mark: 1]
18N.3.hl.TZ0.d.ii
The presence of very small amounts of lead in calcium-based antacids can be determined using inductively coupled plasma-mass spectroscopy (ICP-MS).
Chelating agents can be used to treat heavy metal poisoning.
An aqueous lead(II) ion reacts with three ethane-1,2-diamine molecules to form an octahedral chelate ion.
Outline why the chelate ion is more stable than the reactants.
[1]
Markscheme
increase in entropy
OR
ΔS > 0/ΔS positive ✔
Accept “ΔG < 0” but not “ΔH < 0”.
