Question 22N.2.hl.TZ0.d.vi
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.2.hl.TZ0.d.vi |
| Level | hl | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate | Question number | d.vi | Adapted from | N/A |
Ammonium nitrate, NH4NO3, is used as a high nitrogen fertilizer.
Cold packs contain ammonium nitrate and water separated by a membrane.
Calculate the standard Gibbs free energy change, ΔG⦵, in kJ mol−1, for the dissolution of ammonium nitrate at 298 K. Use sections 1 and 19 of the data booklet as well as your answer for question part (d)(v).
If you did not obtain an answer in (d)(v), use 102.3 J mol−1 K−1, although this is not the correct answer.
[1]
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−6.70 «kJ mol−1» ✔
If 102.3 J mol−1 K−1 is used then answer is −4.80 KJ mol−1.
About 80% of students applied the appropriate equation to calculate the free energy change for the reaction from the entropy and enthalpy change values previously found. As might have been predicted quite a few candidates failed to convert the J of the previous calculation into kJ, and a handful left the temperature as Celsius.
