Maxwell-Boltzmann distribution and temperatureAQA A-Level Chemistry: Mind map

Exam questions on Maxwell-Boltzmann distribution and temperature

1. The distribution of molecular energies in a sample of a gas at 300 K is described by a Maxwell–Boltzmann distribution curve, in which the number of molecules is plotted against their energy. The same sample is then heated to 310 K. A reaction of this gas has an activation energy that is much greater than the most probable molecular energy.
   Explain the significance of the area under the curve to the right of the activation energy.2 marks
2. A student investigates how temperature affects the rate of the reaction between sodium thiosulfate solution and dilute hydrochloric acid, which forms a precipitate of sulfur. She mixes 50.0 cm³ of 0.10 mol dm⁻³ sodium thiosulfate solution with 5.0 cm³ of 1.0 mol dm⁻³ hydrochloric acid and measures the time taken for a cross viewed through the mixture to disappear. At 20 °C the time is 64 s and at 30 °C the time is 31 s.
   Suggest two ways in which the reliability of the investigation could be improved.2 marks
3. A gas-phase reaction between two gases is carried out at constant volume at 300 K and at 310 K. At 300 K, 1.0 × 10⁻⁸ of the molecules in the mixture have energy equal to or greater than the activation energy. At 310 K the proportion is 1.8 × 10⁻⁸.
   Calculate the factor by which the proportion of molecules with energy equal to or greater than the activation energy increases, and use it to estimate the effect on the rate of reaction.3 marks