Collision Theory
and
Rates of Reaction

Collision Theory!
In order for a reaction to occur:
• Two reactants must collide
• The collision must have enough energy

What is the rate of a reaction?
• The rate of reaction is the speed at which a
reaction occurs or how fast it occurs.
• There are certain things that can impact this
rate.

Factors that affect the rate of reaction
Think!
• What are some ways we can increase the
speed of a reaction?
• And how do these reasons relate to collision
theory?

Factors that Affect Rate of Reaction
Chemical nature
of Reactants Temperature
Concentration
of Reactants
Presence of
Catalyst
Surface Area
Pressure

Chemical nature of Reactants
 some reactants are more/less reactive then others
Gold is much less
reactive then zinc
In HCl (aq)
Families of elements
tend to undergo the
same types of
reactions, but at
different rates

Concentration of Reactants
 Higher Concentration = faster reaction
• particles more likely to collide

Surface Area of Reactants
 Higher Surface Area = greater rate of reaction
• Particles more likely to collide

Temperature
 Higher Temperature= greater rate of reaction
Particles move faster, so more likely to collide

Presence of a Catalyst
 A substance that speeds up a reaction without
being a reactant or being used up

Pressure
 A higher pressure forces the particles closer
together.
• More chance of particles colliding and reacting.