Maxwell–Boltzmann Distributions (AQA AS Chemistry): Revision Note

Maxwell-Boltzmann Distribution Curve - Temperature

Maxwell-Boltzmann distribution curve

• A Maxwell–Boltzmann distribution curve is a graph that shows the distribution of particle energies at a given temperature

• In a sample of gas, only a small number of particles have very low or very high energy, while most particles have energies around the middle of the distribution

• The graph shows that only a small proportion of molecules in the sample have enough energy for an effective collision and for a chemical reaction to take place

Changes in temperature

• When the temperature of a reaction mixture increases, the particles gain more kinetic energy

• As a result, the particles move faster and collide more frequently

  • In addition, a greater proportion of particles have energy equal to or greater than the activation energy, so a higher proportion of collisions are successful

• On a Maxwell–Boltzmann distribution curve, increasing the temperature causes the curve to flatten and the peak to shift to the right

• Therefore, increasing the temperature increases the rate of reaction because:

  • Particles have more kinetic energy, so they move faster and collide more frequently

  • A greater proportion of particles have kinetic energy greater than or equal to the activation energy, resulting in more successful collisions