Energy and Chemical Changes
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
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!
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
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
Energy in Chemical Reactions Exothermic Endothermic Energy Released Act. Energy Act. Energy Energy Absorbed Reactants Products Reactants Products