Maxwell-Boltzmann Distributions – temp and catalyst
Kinetics Worksheet
Maxwell-Boltzmann Distribution
1. A Maxwell Boltzmann distribution is drawn on the axis below.
a) Add labels the axis on the distribution;
See graph above for labels.
b) Label the most probable energy (Eₚ) and mean energy (Eₘ) on the distribution.
c) Describe and explain the shape of the distribution.
- The line starts at the origin as no molecules have no energy.
- The line rises until it reaches a more probable energy and then falls.
- It is asymptotic on the right as there is no theoretical maximum energy.
2. Temperature can affect the distribution.
a) Sketch a second distribution on the graph, showing what would happen if you were to increase the temperature. Label it T2.
b) Sketch a third distribution on the graph, showing what would happen if you were to decrease the temperature. Label it T3.
b) Sketch a third distribution on the graph, showing what would happen if you were to decrease the temperature. Label it T3.
c) With reference to your graph, explain why the rate of reaction increases when you increase the temperature.
- The area under the T2 graph to the right of Ea is larger than the area under the T1 graph to the right of Ea.
- This means that more molecules have more energy than the activation energy, which results in a larger proportion of the collisions being successful.
3. Catalysts can also be used to increase the rate of reaction. By adding an extra label to your graph, explain why the rate of reaction increases when you add a catalyst.
Answer
- Adding a catalyst reduces the activation energy.
- The area under T1 to the right of Ea (catalysed) is larger than the area under T1 to the right of Ea.
- This means that more molecules have more energy than the activation energy, which results in a larger proportion of the collisions being successful.