topic c5- energy changes

• exothermic reactions

  energy EXITS the reaction into the surroundings
• examples if exothermic reactions

  • burning fuels (combustion)
  • acid + alkali (neutralisation)
• real life uses of exothermic reactions

  • hand warmers
  • self heating cans
• endothermic reactions

  energy ENTERS the reaction from the surroundings
• examples of endothermic reactions

  • thermal decomposition
  • citric acid + sodium hydrogencarbonate
• real life uses of endothermic reactions

  • sports injury packs (ice packs)
• exothermic reaction profile 


  exothermic reaction

  
• endothermic reaction profile 


  endothermic reaction

  
• activation energy 


  the energy required to start the reaction ~
• exothermic reactions lose

  energy
• endothermic reactions gain

  energy
• exothermic reactions

  O + O -> OO + energy released

  ^

  l

  strong bond formed
• bond forming

  • when bonds are formed
  • energy exits the reaction
  • this is an exothermic reaction
• endothermic reactions

  OO + ->(energy supplied) O + O

  ^ ^

  l l

  strong bond bond broken
• bond breaking

  • energy is required to break bonds
  • this energy enters the reaction from the surroundings
  • this is an endothermic reaction