The Collision Theory

1. What is the Collision Theory?

The Collision Theory explains how reaction rates are affected by particle interactions.

• Particles in a reaction mixture are in constant random motion.
• Collisions between particles may lead to a reaction.
• Only effective collisions result in the formation of products.

2. Requirements for an Effective Collision

For a reaction to occur, colliding particles must:

✅ Have sufficient kinetic energy (equal to or greater than the activation energy $(Ea)).$

✅ Be correctly oriented when they collide.

3. Factors Affecting Collision Rate

• More effective collisions → Faster reaction.
• Smaller particles react faster (e.g., dust reacts more violently than larger crystals).
• Higher temperature, concentration, or pressure increases the number of effective collisions.

4. Collision Theory in Symbols

$\text{Reaction Rate} \propto (\text{Number of effective collisions per unit time})$

$\propto (\text{Particles with correct orientation})$

$\propto (\text{Particles with sufficient energy (}E_a\text{)})$

5. Key Takeaways

✅ Reactions occur when particles collide with enough energy and correct orientation.

✅ More frequent and effective collisions = Faster reaction.

✅ Increasing temperature, concentration, or surface area increases reaction rate.