DP Chemistry (first assessment 2025)
Question 19M.2.SL.TZ1.b(iii)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.SL.TZ1.b(iii) |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | b(iii) | Adapted from | N/A |
b(iii).
[Maximum mark: 2]
19M.2.SL.TZ1.b(iii)
Apart from a greater frequency of collisions, explain, by annotating your graphs in (b)(ii), 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
Explaining why temperature increase caused an increase in reaction rate was generally incorrectly answered with most students failing to mention “activation energy” in their answer or failing to annotate the graph.
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.