Maxwell-Boltzmann Distribution
Chemistry: AQA A Level, topic 1.5.2
The Maxwell-Boltzmann Distribution of Energies
The Maxwell-Boltzmann distribution of energies is a handy little graph showing the energy distribution of all the molecules in a gas.
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The graph
- The number of molecules is on the y-axis.
- The kinetic energy of the molecules is on the x-axis.
The origin
- No molecules have zero energy, so the curve passes through the origin at (0,0).
The peak
- There is a peak in the middle.
- This represents the most likely energy of any molecule.
- There are more molecules with this energy than with any other energy.
The area under the graph
- The area under the graph gives the total number of molecules.
- You can think of this as like adding up the number of molecules with every particular energy.
Molecule energies
- The average energy is to the right of the maximum (peak).
- The tail of the graph is asymptotic to the x-axis.
- This means it tends to zero, but never touches the x-axis.
- This reflects that there is a small possibility of having a very high energy molecule.
Activation energies
- We can mark the activation energy on the Maxwell-Boltzmann distribution. This allows us to view the number of molecules with the energy to react.
- On the left-hand side of the activation energy mark, molecules have less energy than the activation energy and so they can't react.
- On the right-hand side, molecules have more energy than the activation energy and so they can react.
Test yourself on Maxwell-Boltzmann Distribution
The peak on the Maxwell-Boltzmann distribution represents what?
What represents the total number of molecules in the Maxwell-Boltzmann graph?
What is the difference in the area under the Maxwell-Boltzmann distribution at high and low temperatures?