| Date | November 2009 | Marks available | 1 | Reference code | 09N.1.hl.TZ0.17 |
| Level | HL | Paper | 1 | Time zone | TZ0 |
| Command term | Determine | Question number | 17 | Adapted from | N/A |
Question
Which ionic compound has the most endothermic lattice enthalpy?
A. NaCl
B. KCl
C. NaF
D. KF
Markscheme
C
Examiners report
This question on the effect of ionic radius on lattice enthalpy proved to be quite challenging, with a Difficulty Index of 43%, with many students considering that the larger potassium ion would give rise to a more endothermic lattice enthalpy than the smaller sodium ion.
