1. Reaction Rates

2. Kinetics is the branch of chemistry dealing with reaction rates.
Kinetics help chemists understand underlying mechanism by which the reaction occurs.

3. Reaction Rates rate at which a chemical reaction takes place
measured by the rate of formation of a product or disappearance of a reactant
Particles must collide in order to react.
rate of a rxn changes with time during the rxn
fastest at beginning and slowest at end

4. Factors Affecting Rate
concentration
pressure
temperature
surface area
catalysts

6. Concentration Reaction rates increase when concentrations increase.
More particles(greater concentration) = more likely collisions will occur.
As reaction proceeds, reactants are consumed, concentration declines, and rate decreases

7. Pressure Doubling the pressure of a gas doubles its concentration
So reaction rate increases

8. Temperature Greatly effects rate
When temp high, particles move faster so more collisions
More collisions = increased rate

9. Surface Area More surface area = more collisions
More collisions = higher rxn rate
Smaller particles gives more surface area
So powder form has highest rate

10. Reaction Pathways and Activation
Particles must collide with enough energy to overcome the repulsion of their electrons.
Minimum energy two colliding particles need to react is activation energy, Ea .

11. Catalysts Speed up reaction Reduce activation energy
Not changed or used in the reaction

12. Enzymes Proteins that catalyze metabolic activity Example:
lactase catalyzes reaction of lactose
People that don’t produce lactase are lactose intolerance

13. Bombardier Beetle