The Role of the Arrhenius Factor in Collision Theory
In collision theory, three critical conditions must be met for a chemical reaction to occur:
- Collision Frequency: Reactant particles must collide with one another.
- Proper Orientation: The particles must align correctly during the collision to allow bonds to break and form.
- Sufficient Energy: The particles must possess enough kinetic energy to overcome the activation energy barrier ($E_a$).
The Arrhenius factor, $A$, quantifies the first two conditions: how often particles collide and how frequently those collisions occur with the proper orientation.
Example
- For small, simple molecules, $A$ tends to be large because most collisions have favorable orientations.
- In contrast, $A$ is smaller for large, complex molecules, where fewer collisions occur in the correct orientation.
Hint
Small increases in temperature can cause significant changes in reaction rates due to the sensitivity of the exponential term $e^{-\frac{E_a}{RT}}$ to temperature.
