COLLISION THEORY

Chemical Reaction Rate

The speed at which reactants are transformed into products over a given period of time, measured in mol/L·s.

Collision Theory

States that chemical reactions occur only when reacting particles collide with sufficient energy and correct orientation.

Activation Energy (Ea)

The minimum amount of energy required for colliding particles to break bonds and initiate a chemical reaction.

Effective Collision

A collision between particles that results in the formation of product molecules due to proper energy and alignment.

Conditions for a Chemical Reaction

Reactant particles must physically collide, but not all collisions result in a reaction. Two mandatory conditions must be satisfied simultaneously for a collision to be effective.

Effective Collision Condition

The colliding particles must have energy greater than or equal to the activation energy (Ea) and the correct alignment to form products.

Ineffective Collision

A collision with insufficient energy or incorrect alignment, causing the particles to rebound without forming products.

Factors Affecting Reaction Rate

Concentration, temperature, and particle size.

Concentration

Higher concentration means more reactant particles in a given volume, increasing particle crowding and collision frequency.

Effect of Concentration on Reaction Rate

Higher concentration increases the reaction rate because more collisions per second lead to more effective collisions per unit time.

Temperature

Higher temperature increases kinetic energy, causing particles to move faster and increasing the fraction of particles with energy greater than or equal to Ea.

Effect of Temperature on Reaction Rate

Higher temperature increases the reaction rate by significantly increasing collision frequency and the percentage of successful collisions.

Particle Size

Smaller particles provide a greater exposed surface area for the same mass, exposing more reactive sites to collisions.

Effect of Particle Size on Reaction Rate

Smaller particles increase the reaction rate because the greater exposed surface area allows more simultaneous collisions between reactant molecules.

Collision Theory Summary

Chemical reactions require collisions with proper orientation and energy greater than or equal to the activation energy (Ea).

Concentration Summary

Higher concentration means more particles per volume, resulting in higher collision frequency.

Temperature Summary

Higher temperature means faster particle movement and higher kinetic energy, resulting in more effective collisions.

Particle Size Summary

Smaller particles have a larger surface area, increasing collision contact points.