DP Chemistry (last assessment 2024)
Question 19M.2.hl.TZ1.g(ii)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.hl.TZ1.g(ii) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | g(ii) | Adapted from | N/A |
g(ii).
[Maximum mark: 1]
19M.2.hl.TZ1.g(ii)
This question is about sodium and its compounds.
Sodium peroxide is used in diving apparatus to produce oxygen from carbon dioxide.
2Na2O2 (s) + 2CO2 (g) → 2Na2CO3 (s) + O2 (g)
Outline why bond enthalpy values are not valid in calculations such as that in (g)(i).
[1]
Markscheme
only valid for covalent bonds
OR
only valid in gaseous state [✔]
Examiners report
The majority of candidates referred to “bond enthalpy values are average”, rather than not valid for solids or only used for gases.
