The mechanism of reactions

1. The Maxwell-Boltzmann Distribution

• The Maxwell-Boltzmann distribution curve shows how the kinetic energy of particles in a reaction system is distributed.
• X-axis: Kinetic energy of molecules.
• Y-axis: Number of particles. 🔹 Key Features of the Curve:

✅ The curve always starts at the origin (all molecules are in motion).

✅ The peak represents the most probable energy (most molecules have this energy).

✅ Shaded area beyond activation energy $(Ea):$ Molecules with enough energy to react.

2. Factors Affecting Reaction Rate (Using Maxwell-Boltzmann Distribution)

a) Effect of Temperature

✅ Higher temperature → More kinetic energy → Faster reaction.

✅ Graph shifts right (more particles exceed activation energy).

✅ More frequent and effective collisions occur.

b) Effect of Concentration (or Pressure for Gases)

✅ Higher concentration → More particles per unit volume.

✅ More collisions per second → Higher reaction rate.

✅ Graph is taller but maintains the same shape.

c) Effect of a Catalyst

✅ Lowers activation energy $(Ea)$→ More particles have enough energy to react.

✅ Vertical dotted line $(Ea)$ shifts left on the graph.

✅ Increases the rate of effective collisions.

3. Key Takeaways

✅ Reaction rate depends on the number of particles with energy ≥ activation energy.

✅ Higher temperature, concentration, or a catalyst increases reaction rate.

✅ The Maxwell-Boltzmann curve helps visualise energy distribution in reactions.