1. Review of Alka Seltzer Lab
“Reaction Rates”
Review of Alka Seltzer Lab

2. Collision Theory Reactions can occur:
Very fast – such as a firecracker
Very slow – such as the time it took for dead plants to make coal
A “rate” is a measure of the speed of any change that occurs within an interval of time

3. Collision Model
Key Idea: Molecules must collide to react.

4. Factors Affecting Rate
Temperature
Increasing temperature always increases the rate of a reaction.
Surface Area
Increasing surface area increases the rate of a reaction
Concentration
Increasing concentration USUALLY increases the rate of a reaction
Presence of Catalysts:
Pressure
Increasing the pressure increases the rate of the reaction.

5. Catalysts
Catalyst: A substance that speeds up a reaction, without being consumed itself in the reaction
Inhibitors – interfere with the action of a catalyst; reactions slow or even stop

6. Evidence of a Chemical Reaction: color change odor change temperature change bubbles or gas production solid formation

7. http://player. discoveryeducation. com/index. cfm

8. http://player. discoveryeducation. com/index. cfm