Reaction Rates

1. Reaction Rates Chapter 12.1 and 12.4 of A Natural Approach to Chemistry

2. Rates of Reactions • How fast does a reaction occur?

3. Why Do We Care? Sometimes we need to slow reactions down. Sometimes we need reactions to happen quickly.

4. Why Do We Care? How do we know if a reaction is going to occur quickly or slowly? Better yet, how can we control the rate of a reaction?

5. Rate of Reaction Rate of Reaction - how fast a reaction occurs -how quickly the amount of reactants __________ -how quickly the amount of products __________ decrease increase

6. Collision Theory Collision Theory – In order to react, reactant molecules must collide with each other How does this relate to reaction rates? In order to increase reaction rate, we must increase the number of collisions.

7. Factors Affecting Reaction Rate 1) Temperature – hotter temperatures mean: ____________ molecules molecular collisions ___________ Reaction rate __________ faster increase increases

8. Factors Affecting Reaction Rate Which of these will have more collisions? Low Concentration High Concentration

9. Factors Affecting Reaction Rate 2) Concentration – higher concentration means: _______ reactant molecules molecular collisions ___________ Reaction rate __________ more increase increases

10. Factors Affecting Reaction Rate Which of these will have more collisions? Low Surface Area High Surface Area

11. Factors Affecting Reaction Rate 3) Surface Area – higher surface area means: _______ reactant molecules available for collisions molecular collisions ___________ Reaction rate __________ more increase increases

12. Factors Affecting Reaction Rate

13. Factors Affecting Reaction Rate 4) Catalyst – molecule that ____________ the reaction rate without getting used up in the reaction itself increases How does it do this? - It lowers the activation energy of the reaction