Endothermic and Exothermic Reaction

A: -Endothermic: absorb energy from surrounding
     -Exothermic: release energy to surrounding
  
     Ex: Instant ice pack absorb energy and are Endothermic reaction
            Explosions release energy are exothermic reaction

     -Molecules are held together by chemical bonds
       -Add energy to break bonds---->Endothermic
       -Give off energy to form bonds--->Exothermic
      *Enthalpy, "H" is the heat contained in the system

B: We can chart the potential energy of the chemicals as they change from reactants to products

    -Reactants start with a certain amount of energy, energy is added to start the reaction and  then energy is released as the reaction processes

  -Energy of reactant: total potential energy of all reactants in the reactions
  -Energy of product: total potential energy of all products in the reactions
  -Energy of activated complex: potential energy of the transition state between reactant-product
  -Activation energy:  the energy that must be added to get the reaction to progress
  -Delta H: the change in potential energy during the reaction


C: The energy in Equation
     Ex: CH4+2O2--->CO2+2H2O+812KJ
            higher               lower
            energy             energy

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