Exothermic: To be able to explain reactions in terms of bond energy.



  • Heat is given out
  • Temperature rises.
  • "EXO"thermic , think of the exo as exit- given out- running out the exit.
  • Some examples of exothermic reactions are:
  • burning
  • neutralisation reactions between acids and alkalis
  • the reaction between water and calcium oxide

  • transfer energy to the surroundings.
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  • temperature drops
  • Energy is absorbed from the surroundings.
  • examples of endothermic reactions are:
  • electrolysis
  • the reaction between ethanoic acid and sodium carbonate
  • the thermal decomposition of calcium carbonate in a blast furnace
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Reversible Reactions

  • In a reversible reaction, the products can react to produce the original reactants again.
  • For example,

    ammonium chloride Equilibrium symbol ( + hydrogen chloride

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La Chatliers Principal

" any cnage you make to the system, the system will try to counteract then eg: making sandwiches , then undo them."

  • For maximum yield we have to shift equilibrium to right hand side.
  • Increase Pressure- system tries to decrease pressure.
  • Change temperature- system tries to decrease temperature this favours the endothermi reaction.
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