calorimetry

• Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction. By knowing the change in heat, it can be determined whether or not a reaction is exothermic (releases heat) or endothermic (absorbs heat)
• When recorded and plotted on a graph, data can be

  extrapolated to the exact point at which the reaction starts, giving a more accurate value for the

  change in temperature.

  
• q = mc∆T

  where q = energy change (J) heat exchanged with the surroundings

  m = mass (g) mass of the substance heated or cooled

  c = specific heat capacity of the substance that is heated or cooled, energy required to raise the temperature (J g-1K -1) water is 4.18

  ∆T = temperature change (K)
• specific heat capacity - the energy required to raise 1 g of substance by 1 K without a change of state
• Sources of Error

  • ∆H values found using calorimetry are never completely accurate, since energy is easily lost from the system.
  • Heat loss can occur due to conduction, convection or inaccuracies in measuring temperatures.
  • The heat loss to the surroundings can be reduced by putting a lid on the calorimeter and insulating the outsides of the calorimeter, using an insulator like polystyrene.
  • The specific heat capacity of the calorimeter is not taken into account so this leads to inaccuracies in the calculation.