Question 19M.2.sl.TZ2.2d
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.sl.TZ2.2d |
| Level | sl | Paper | 2 | Time zone | TZ2 |
| Command term | Outline | Question number | d | Adapted from | N/A |
The thermal decomposition of dinitrogen monoxide occurs according to the equation:
2N2O (g) → 2N2 (g) + O2 (g)
The reaction can be followed by measuring the change in total pressure, at constant temperature, with time.
The x-axis and y-axis are shown with arbitrary units.
The experiment gave an error in the rate because the pressure gauge was inaccurate. Outline whether repeating the experiment, using the same apparatus, and averaging the results would reduce the error.
[1]
no AND it is a systematic error/not a random error
OR
no AND «a similar magnitude» error would occur every time [✔]
This question was well answered by nearly 70 % of the candidates reflecting a good understanding of the impact of systematic errors. Some students did not gain the mark because of an incomplete answer. The question raised much debate among teachers. They worried if the error was clearly a systematic one. However, a high proportion of candidates had very clear and definite answers. In Spanish and French, the wording was a bit ambiguous which caused the markscheme in these languages to be more opened.
