Factors Effecting Reaction
Rate
Collision Theory
 In
order to react molecules and atoms
must touch each other.
 They must hit each other hard enough to
react.
 Anything that increase these things will
make the reaction faster.
Things that Effect Rate
 Temperature
- Higher temperature faster particles.
- More and harder collisions.
- Faster Reactions.
 Concentration
- More concentrated closer together
the molecules.
- Collide more often.
- Faster reaction.
Things that Effect Rate
 Particle
size
- Molecules can only collide at the
surface.
- Smaller particles bigger surface area
per volume.
- Smaller particles faster reaction.
Orientation
 Colliding
alone is not enough to
guarantee reaction
 Relative orientations of the molecules
may determine if the energy gets to the
right place or if they are suitably oriented
to form the new bonds
 As temp increases, the number of
collisions increases as does the fraction
that are oriented correctly
Activation Energy
A
certain amount of energy must be
available to “propel” the molecules from
one chemical state to another
 This energy barrier is called the
Activation Energy (Ea)
 Arrangement of atoms that has this
maximum energy is called the activated
complex
Energy Profile
Energy
Reactants
Products
Reaction coordinate
Energy
Activation Energy Minimum energy to
make the reaction
happen
Reactants
Products
Reaction coordinate
Energy
Activated
Complex or
Transition State
Reactants
Products
Reaction coordinate
Energy
Reactants
Overall energy
change
Products
Reaction coordinate
Boltzmann Distribution
 In
any sample of a substance, there
exists a distribution of velocities of the
particles
 Only some the particles have sufficient
energy to reach the minimum activation
energy
 As
the temperature increases, the
number of molecules with minimum
activation energy increases