A chemist records Maxwell–Boltzmann energy distributions for the same gas at and at

CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics

Problem

A chemist records Maxwell–Boltzmann energy distributions for the same gas at

300\,\text{K}

and at

400\,\text{K}

. The activation energy for a certain reaction is the same in both cases. Which explanation best accounts for the observed increase in reaction rate when the temperature is raised from

300\,\text{K}

400\,\text{K}

? (a) The total area under the

400\,\text{K}

Maxwell–Boltzmann curve is greater, so more gas particles are available to collide. (b) A larger fraction of particles at

400\,\text{K}

possess kinetic energies greater than the activation energy. (c) Gas molecules move faster at

400\,\text{K}

, leading to more frequent collisions even if the fraction of high-energy particles is unchanged. (d) The activation energy of the reaction becomes lower at

400\,\text{K}

, enabling more collisions to result in reaction.

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