# Explain how the Maxwell–Boltzmann distribution of molecular energies can be used to account for the observation that a small increase in temperature produces a disproportionately large increase in the rate of a chemical reaction.

> IB DP Chemistry Higher Level (2023 syllabus) — R2.2 How fast? The rate of chemical change · Explain · 4 marks

## Mark scheme (4 marks)

1. The Maxwell–Boltzmann distribution shows the spread of kinetic energies among molecules at a given temperature, with only a fraction of molecules possessing energy greater than or equal to the activation energy.
2. When temperature increases, the distribution curve shifts to the right (towards higher energies) and flattens, so the peak moves to a higher energy value.
3. The area under the curve to the right of the activation energy increases significantly, meaning the fraction of molecules with energy ≥ Ea increases markedly even for a small temperature rise.
4. Because the rate depends exponentially on the fraction of molecules above Ea (as in the Arrhenius equation, k = Ae^(−Ea/RT)), even a modest temperature increase produces a disproportionately large increase in the rate constant and hence the reaction rate.

## Key terms

- [Maxwell–Boltzmann distribution](https://www.gradenine.co.uk/glossary/maxwell-boltzmann-distribution)

## Related

- [Revision notes for IB DP Chemistry Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-maxwell-boltzmann-distribution-of-5c2a4fbc) · Published by Druglandscape Ltd.