1. Thermochemistry 3 Calorimetry & Heat of Formation

2. Calorimetry and Heat Capacity Temperature change occurs when a system gains or looses energy as heat Experiment carried out in a calorimeter Change in heat energy is calculated from temperature change Pressure is constant, so enthalpy is found (  H =  E + P  V) amount of heat released by reaction = heat gained by calorimeter + heat gained by sol’n Calorimetry – an experimental method to find the energy change of a chemical or physical process

3. Bomb Calorimeter Material is combusted (burnt) inside a bomb calorimeter Box is sealed, with oxygen atmosphere Burnt material heats the water Energy change is found from temp change of water Constant volume, not constant pressure, so gives  E (  H =  E + P  V)

4. Specific Heat Capacity Heat capacity, (C) is the amount of energy it takes to heat something a given amount Its easier to heat aluminium up than water. Water has a greater heat capacity than aluminium

5. Specific Heat Capacity The amount of heat, q, necessary to increase temp of a given number of moles of a substance is: where C = Specific heat  T = change in temperature So Molar heat capacity (C m) ~ amount of needed heat to increase 1 mol substance by 1 o C