Energy and chemical change

• Heat of Reaction (ΔH)


  Define heat of reaction (ΔH) as the energy absorbed or released (per mole) in a chemical reaction.
• Exothermic Reactions

  reactions that release energy State that ΔH < 0 for exothermic reactions, i.e. reactions in which energy is released
• Endothermic Reactions

  reactions that absorb energy o State that ΔH > 0 for endothermic reactions, i.e. reactions in which energy is absorbed
• Activation Energy


  minimum energy needed for a reaction to take place
• Activated Complex


  unstable transition state from reactants to products