Fair testing

• We should eat a balanced diet suitable for our age and lifestyle
• Overeating can lead to obesity
• Nutrients have to be digested before we can absorb and use them
• Fair testing


  • Several variables should be kept constant:
  • Volume of water
  • Mass of food
  • Distance of the flame from the boiling tube
• Sources of error in calorimetry


  • It is difficult to maintain a constant distance between the burning food and the tube, varying the heat loss to the environment
  • It is difficult to minimise heat loss when transferring the burning food from the flame to the tube
  • In this method it is possible that incomplete burning of the crisp gives an inaccurate measurement of the mass burned
• Bomb calorimeter


  • Sample is burned in a sealed chamber to reduce heat loss to the environment
  • Sample chamber is surrounded by another chamber of water in which the temperature change is measured
  • Sample is burned in pure oxygen to ensure complete combustion