Paper 2 Q2(b) — The Boltzmann distribution curve

Kinetics — shape of the Maxwell–Boltzmann distribution and effect of temperature/catalyst

What the examiners said

“Common errors included not starting the curve at the origin and the right-hand side ending too high, without showing the decrease to be asymptotic, or touching the x-axis and plateauing… The majority drew a suitable curve [for higher temperature]; common errors included the same or higher maximum, the maximum directly below the original.”

Item 1 — drawing the curve

Which set of features describes a correct Maxwell–Boltzmann distribution of molecular energies?

Examiner report: “Errors: not starting at the origin; tail ending too high or plateauing instead of asymptotic.”

Item 2 — raising the temperature

At a higher temperature, how does the curve change?

Examiner report: “For higher T: common errors were the same or higher maximum, or the maximum directly below the original.”

Explore — temperature and the energy distribution

Raise the temperature and watch the peak drop and slide right while the shaded fraction of molecules with energy ≥ E_a grows. Total area stays constant.

Temperature (K): 300 Activation energy E_a: 55

A catalyst would instead move the red E_a line to the left (lower activation energy), enlarging the shaded fraction without changing the curve.

Original reconstruction inspired by the misconceptions described in the Singapore-Cambridge GCE A-Level H1 Chemistry 8873 November 2023 Examiner Report. Not the actual examination question. For classroom exploration.

Made by lookang, using Claude Fable 5. More resources: iwant2study.org