1. Chapter 6 Chemical Reactions
Section 1
The Nature of Chemical Reactions
p. 184

2. Compare exothermic and endothermic reactions
Objectives
Compare exothermic and endothermic reactions
Analyze how a reaction takes place

3. Are you able to predict your parent’s reactions? How do you know?
Think….
Are you able to predict your parent’s reactions? How do you know?

4. I. Chemical reactions change substances – it rearranges atoms
25 O2 + 2 C8H  CO H2O
Products
Reactants
Yields

5. II. Energy and Reaction
Activation Energy – energy amount
needed to start a reaction
A. Energy is needed to break bonds
(heat, electricity, sound, light, etc)
B. Forming bonds releases energy
(sometimes as heat or light)
C. Energy is conserved – chemical
energy – energy is released when a
chemical compound reacts to
produce new compounds

6. 1. Exothermic – reaction where thermal energy is released (heat)
Products have less energy than
reactants
Time
Energy

7. 2. Endothermic – reaction that absorbs thermal energy
Products have more energy
than reactants
Energy
Time