1. Collision Theory & Reaction Rates
Unit 4 – Chemical Reactions & Equations

2. Collision Theory In order to react, particles must COLLIDE
HAVE PROPER ORIENTATION UPON COLLISION
HAVE SUFFICIENT ENERGY UPON COLLISION

3. Collision Theory
NO3(gas) + CO(gas)    NO2(gas) + CO2(gas)

4. Activation Energy of Particles
Activation Energy Ea :
The minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport.

5. Activation Energy of Particles

6. Activation Energy of Particles

7. Reaction Rates Reaction Rate:
The measure of the change in concentration of the reactants or the change in concentration of the products per unit time.

8. How do these reactions compare?

9. How can we measure reaction rates?
Reaction rates must be measured by the change in the amount of reactant or product over time:
TWO COMMON WAYS TO MEASURE REACTION RATE:
Loss of mass of system
Collect a gas that is released
When did this reaction stop?

10. Can we speed up or slow down chemical reactions?

11. Factors that Affect Reaction Rates
Temperature
Concentration of a Reactant
Particle Size
Pressure (when reacting gases)
Adding a catalyst or an enzyme