In the Maxwell-Boltzmann equation for the distribution of molecular speeds, , the exponential term i — States of Matter and Gaseous State Chemistry Question
Question
In the Maxwell-Boltzmann equation for the distribution of molecular speeds, $\frac{1}{N}\frac{dN}{du} = 4\pi \left(\frac{M}{2\pi RT}\right)^{3/2} u^2 e^{-Mu^2/2RT}$, the exponential term $e^{-Mu^2/2RT}$ is known as the Boltzmann factor. What specific physical feature of the distribution curve does this term primarily dictate?
💡 Solution & Explanation
The distribution curve is a product of a $u^2$ term (which dominates at low speeds, causing the initial parabolic rise) and the exponential $e^{-Mu^2/2RT}$ term. At very high speeds ($u$), the negative exponential term dominates and decays rapidly towards zero, dictating the steep drop-off in the fraction of molecules with extremely high speeds.