energy changes

• exothermic reactions transfer energy to the surroundings, rise in temperature
• exothermic reactions are combustion and neutralisation
• exothermic reactions are used in hand warmers and self heating cans
• endothermic reactions take in energy, fall in temperature
• endothermic reactions are thermal decompostion
• endothermic reactions are used in sports injury packs
• in exothermic reactions the energy released by forming bonds is greater than the energy to break them
• bond energy = energy required to break bonds - energy released by forming bonds
• exothermic reaction profile

  
• endothermic reaction profile