chemical energetics

• exothermic reactions

  Exothermic reactions give out energy. So there is a temperature rise.

  e.g combustion of fuels

  reaction between hydrogen and oxygen
• eg of combustion of fuels

  C+O2-->CO2

  CH4+2O2-->CO2+2H2O(METHANE+OXYGEN->METHANEOXIDE)

  CaO+H2O-->Ca(OH)2(calciumoxide+water->calciumhydrooxide)

  respiration:C6H12O6+O2-->CO2+H2O
• ENERGY LEVEL DIAGRAM

  REACTANTS ENERGY IS ALWAYS GREATER THAN PRODUCT

  
• ENDOTHERMIC

  -HEAT IS ABOSRBED FROM THE SURROUNDINGS CAUSING TEMPERATURE DECREASE IN THE SURROUNDING

  e.g 1-melting 2- thermal decomposition: CaCO3-->CO2+CaO

  (calcium carbonate>calciumoxide+carbondioxide)

  3-photosynthesis: CO2+H20-->C6H12O6+O2

  (CARBONDIOXIDE+WATER->GLUCOSE+OXYGEN
• .

  .

  
• .

  .

  
• .

  .

  
• .

  .

  
• Bond making and breaking

  Bond making is exothermic

  bond breaking is endothermic
• neutralisation 


  Always exothermic
• endothermic


  Temperature decreases

  energy taken in
• Mcq 


  When an acid is added to an alkali the temperature rises. Which words describe this reaction?

  A decomposition and endothermic

  B decomposition and exothermic

  C neutralisation and endothermic

  D neutralisation and exothermic

  Answer:D
• Mcq

  Which process is not exothermic?

  A burning a fossil fuel

  B obtaining lime from limestone

  C radioactive decay of 235U

  D reacting hydrogen with oxygen

  answer B
• Neutralisation 


  Reaction of acid and alkali to form salt and water(both have 7 ph)
• Mcq


  MCQ

  
• MCQ


  Mcq

  
• Endothermic 


  Distilling petroleum