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
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

5. Concentration Particles must collide in order to react.
Reaction rates increase when concentrations increase (or are larger).
More particles(greater concentration) = more likely collisions will occur.
If concentration is doubled # of collisions will double.
As reaction proceeds, reactants are consumed, concentration declines, and rate decreases

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

7. Temperature Greatly effects rate
Particles move faster so more collisions
More collisions = increased rate

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

9. Reaction Pathways and Activation
For 2 particles to rxt, they must collide violently enough to overcome the repulsion of their electrons.
Only particles enough kinetic energy are likely to rxt.
activation energy, Ea -minimum energy 2 colliding particles need to rxt.

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

11. Enzymes Proteins that catalyze metabolic activity
ex) lactase catalyzes reaction of lactose(sugar in milk).
People that don’t produce lactase are lactose intolerance