Energy of Chemical Reactions

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Energy of Chemical Reactions

• 2-4

2

• Chemical reactions are either endothermic or
  exothermic.

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Exothermic Reactions

• Energy is RELEASED
• Thermic - heat
• Exo - out of
• heat comes out of, or is released, during an
  exothermic reaction
• burning, combustion

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Exothermic Reactionscont

• The energy released was originally stored in the
  molecules of the reactants.
• The energy of the products is less than the
  energy of the reactants

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Endothermic Reactions

• Energy is absorbed
• endo - into
• energy is taken into a reacting substance.
• Usually in the form of heat or light
• Energy of the products is more than the reactants

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Activation Energy

• The energy needed for a reaction to occur
• After reactants have absorbed the activation
  energy, they can form products