Maxwell-Boltzmann distributionsEdexcel A-Level Chemistry: Mind map

Exam questions on Maxwell-Boltzmann distributions

1. A student sketches the Maxwell–Boltzmann distribution of molecular energies for a gas at a fixed temperature, with the number of molecules on the vertical axis and energy on the horizontal axis, and marks the activation energy of a reaction on the energy axis.
   Explain why the curve starts at the origin and why it never touches the energy axis at high energy.2 marks
2. A reaction mixture of gases is heated from 300 K to 310 K, and the rate of the reaction approximately doubles. The student sketches the distribution of molecular energies at the two temperatures on the same axes.
   Explain, using the distributions, why the reaction is faster at 310 K.2 marks
3. A car's catalytic converter contains platinum and rhodium on a solid support. At the temperature of the exhaust gases it converts carbon monoxide and nitrogen monoxide into carbon dioxide and nitrogen: 2CO(g) + 2NO(g) → 2CO₂(g) + N₂(g). Without the catalyst the reaction is far too slow at this temperature.
   Explain, with reference to the Maxwell–Boltzmann distribution, how the catalyst increases the rate of the reaction at the same temperature.3 marks