DP Chemistry (first assessment 2025)
Question 19M.2.SL.TZ1.4b(iv)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.SL.TZ1.4b(iv) |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | b(iv) | Adapted from | N/A |
b(iv).
[Maximum mark: 2]
19M.2.SL.TZ1.4b(iv)
(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.
Syllabus sections
Reactivity 2. How much, how fast and how far? » Reactivity 2.2—How fast? The rate of chemical change » Reactivity 2.2.4—Activation energy, Ea, is the minimum energy that colliding particles need for a successful collision leading to a reaction. Construct Maxwell–Boltzmann energy distribution curves to explain the effect of temperature on the probability of successful collisions.