DP Chemistry (last assessment 2024)
Question 19M.2.hl.TZ1.4b(iv)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.hl.TZ1.4b(iv) |
| Level | hl | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | b(iv) | Adapted from | N/A |
b(iv).
[Maximum mark: 2]
19M.2.hl.TZ1.4b(iv)
This question is about the decomposition of hydrogen peroxide.
Hydrogen peroxide decomposes to water and oxygen when a catalyst such as potassium iodide, KI, is added.
2H2O2 (aq) O2 (g) + 2H2O (l)
(b(iv))
Apart from a greater frequency of collisions, explain, by annotating your graphs in (b)(iii), why an increased temperature causes the rate of reaction to increase.
[2]
Markscheme
Ea marked on graph [✔]
explanation in terms of more “particles” with E ≥ Ea
OR
greater area under curve to the right of Ea in T2 [✔]
Examiners report
The majority of candidates earned at least one mark, many both marks. Errors included not annotating the graph with Ea and referring to increase of kinetic energy as reason for higher rate at T2.
