Question 22N.2.hl.TZ0.d.iii
| Date | November 2022 | Marks available | [Maximum mark: 3] | Reference code | 22N.2.hl.TZ0.d.iii |
| Level | hl | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate | Question number | d.iii | 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.
The absolute uncertainty in mass of the contents of the cold pack is ±0.01 g and in each temperature reading is ±0.2 °C. Using your answer in (d)(ii), calculate the absolute uncertainty in the mass of ammonium nitrate in the cold pack.
If you did not obtain an answer in (d)(ii), use 6.55 g, although this is not the correct answer.
[3]
«fractional / % uncertainty in ΔT =» / 0.02 / 2«%» ✔
«fractional / % uncertainty in =» / 0.0004 / 0.04«%»
OR
fractional / % uncertainty in is much smaller than uncertainty in ΔT ✔
«2% x 8.01 g =» 0.2 «g» ✔
Award [3] for correct final answer.
Accept range of 0.1 – 0.2 «g».
If 6.55 g used then answer is 0.1 «g».
Whilst this was better tackled than some uncertainty problems have been in recent years, students only gained about half marks on average, though there was a strong link with overall performance. The most common error was not to apply the temperature uncertainty to both recorded temperatures, to give an uncertainty of the change as ±0.4.
