Question 19M.2.hl.TZ1.3d(ii)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.hl.TZ1.3d(ii) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Determine | Question number | d(ii) | Adapted from | N/A |
This question is about sodium and its compounds.
The Born-Haber cycle for sodium oxide is shown (not to scale).
The standard enthalpy of formation of sodium oxide is −414 kJ mol−1. Determine the lattice enthalpy of sodium oxide, in kJ mol−1, using section 8 of the data booklet and your answers to (d)(i).
(If you did not get answers to (d)(i), use +850 kJ mol−1 and +600 kJ mol−1 respectively, but these are not the correct answers.)
[2]
lattice enthalpy = 861 «kJ mol−1» + 2 × 603 «kJ mol−1» −(−414 «kJ mol−1») [✔]
«= +» 2481 «kJ mol−1» [✔]
Note: Award [2] for correct final answer.
If given values are used:
M1: lattice enthalpy = 850 «kJ mol−1» +
2 × 600 «kJ mol−1» −(−414 «kJ mol−1»)
M2: «= +» 2464 «kJ mol−1»
Many candidates earned some credit for ECF based on (d)(i).
