DP Chemistry (last assessment 2024)
Question 19M.2.hl.TZ1.d(iii)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.hl.TZ1.d(iii) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Justify | Question number | d(iii) | Adapted from | N/A |
d(iii).
[Maximum mark: 1]
19M.2.hl.TZ1.d(iii)
This question is about sodium and its compounds.
The Born-Haber cycle for sodium oxide is shown (not to scale).
Justify why K2O has a lower lattice enthalpy (absolute value) than Na2O.
[1]
Markscheme
K+ ion is larger than Na+
OR
smaller attractive force because of greater distance between ion «centres» [✔]
Examiners report
Average performance with answers using atomic size rather than ionic size or making reference to electronegativities of K and Na.
