1. Introduction to Chemical Reactions Making new substances

2. Chemical Reactions are Everywhere CookingRespiration

3. Hair Dye Auto Fuel

4. Clues to a Chemical Reaction Color Change Precipitate Formation

5. Clues to Chemical Reactions Gas Formation Odor

6. Clues to Chemical Reactions Temperature Change Change in Acidity (pH)

7. Representing Chemical Reactions Reactions are shown using chemical equations Solid Sodium combines with Chlorine gas to make solid Sodium Chloride: 2Na (s) + Cl2 (g)  2NaCl

8. Parts of Chemical Equations

9. Symbols used in Chemical Equations SymbolPurpose +Separates more than one reactant or product  Separates reactants from products. Indicates direction of reaction (s)Identifies a solid state (aq)Identifies that something is dissolved in water (l)Identifies liquid state (g)Identifies gaseous state

10. Endothermic and Exothermic Reactions “Exo-” means exit Energy is released by the reaction New products feels warmer “Endo-” means enter Energy is absorbed by the reaction New product feels cooler

11. Endothermic and Exothermic Reactions

12. Activation Energy Energy used to initiate a reaction Examples: 1.Adding Heat 2.Mixing or Stirring 3.Adding a catalyst Catalyst - something that speeds up a reaction without interfering with the reaction.