1. 7.4 Reaction Rates Key Concepts: What does a reaction rate tell you?
What factors cause reaction rates to change?

2. 7.4 Reaction Rates
A. Reaction Rate 1. Rate at which reactants change into products over time. 2. Tells you how fast the reaction is going: a. How fast the reactants are being consumed b. How fast the products are being formed c. How much energy is being absorbed or released

3. 7.4 Reaction Rates
B. Factors Affecting Reaction Rates 1. Temperature a. Increasing the temperature will increase the rate of reaction. b. Due to the particles moving faster c. which will cause more collisions d. so the reaction occurs more quickly.

4. 7.4 Reaction Rates
e. Examples 1). Boiling water- more heat, eggs will cook more quickly.
2). Keep food from spoiling

5. 7.4 Reaction Rates
2. Surface Area a. The smaller the particle size of a given mass, the larger its surface area. b. The larger the surface area, the greater exposure of reactants to one another, c. which will cause more collisions d. so the reaction occurs more quickly.

6. 7.4 Reaction Rates
e. Example Alka seltzer- whole piece vs. a bunch of pieces

7. 7.4 Reaction Rates
3. Stirring a. Agitating the reaction which causes the reaction rate to increase. b. This is due to the greater exposure of reactants to one another, c. which will cause more collisions d. so the reaction occurs more quickly.

8. 7.4 Reaction Rates
e. Example Soaking clothes vs. washing machine- the stirring of the detergent with the clothes will make the stains come out.

9. 7.4 Reaction Rates
4. Concentration a. When the number of particles in a given volume is increased, the reaction rate increases. b. This is due to the more reacting particles in a given volume, c. which will cause more collisions d. so the reaction occurs more quickly.

10. 7.4 Reaction Rates Dying fabric with more concentrated solution will
e. Example
Dying fabric with more concentrated solution will
cause the material to color more quickly

11. 7.4 Reaction Rates
5. Catalysts a. Substance that affects the reaction rate without being used up in the reaction. b. Can speed up a reaction or enable a reaction to occur at a lower temperature. c. Lower the amount of energy required for effective collisions between the reacting particles.

12. 7.4 Reaction Rates
d. Example Enzymes that are used for digestion of food.

13. 7.4 Reaction Rates
Assignment: Read Fertilizer: Friend or Foe- Answer questions 7.4 Review p. 215 #1-8 all Read Lab: Rates of Reactions