1. Energy and Chemical Changes

2. How is energy related to chemical change?
Activation energy—The energy that starts a chemical reaction.
ALL chemical reactions need activation energy.
Example: Striking a match

3. What happens to energy DURING a chemical reaction?
ALL chemical reactions release or absorb energy.
How can you tell which one is happening?
Take its temperature!

4. Exothermic Reactions Is energy being released or absorbed?
Release energy.
They always feel hot.
Where does the heat energy come from?
Chemical energy heat energy

5. Endothermic Reactions
Is energy being released
or absorbed?
Endothermic reactions
absorb energy.
They usually feel cold.
Won’t feel cold if heat is
their activation energy.
Where does the heat energy go?
heat energy chemical energy

6. Energy in Chemical Reactions
Exothermic Endothermic
Energy
Released
Act. Energy
Act. Energy
Energy
Absorbed
Reactants
Products
Reactants
Products