DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ1.7
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.hl.TZ1.7 |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Explain, State | Question number | 7 | Adapted from | N/A |
7.
[Maximum mark: 3]
19M.3.hl.TZ1.7
EDTA chelates with Ni2+ (aq).
[Ni(H2O)6]2+ (aq) + EDTA4− (aq) [Ni(EDTA)]2− (aq) + 6H2O (l)
(a)
Explain how entropy affects this equilibrium.
[2]
Markscheme
entropy increases «and the reaction proceeds to the right» [✔]
more species / free molecules are formed
OR
more ways of distributing energy [✔]
Examiners report
There were several incorrect responses that products were more ordered than the reactants.
(b)
State the number of coordinate covalent bonds EDTA forms with Ni2+.
[1]
Markscheme
six [✔]
Examiners report
Proved very challenging with very few candidates knowing the number of coordinate covalent bonds EDTA forms with a nickel ion.
