8.4 - Standard Enthalpy Changes

• enthalpy change

  amount of heat released or absorbed in a reaction at constant pressure
• standard enthalpy change

  reactions done under standard conditions
• standard conditions

  pressure of 100kPa

  298k or 25°C

  solution with concentration 1 mol dm-3

  substances in their standard states
• standard enthalpy change of reaction

  enthalpy change when molar quantities of reactants as stated in the equation react under standard conditions
• standard enthalpy change of combustion

  enthalpy change when one mole of a compound is burnt completely in oxygen under standard conditions
• how is enthalpy change of combustion measured?

  using a bomb calorimeter
• standard enthalpy change of formation

  enthalpy change when 1 mole of a compound is formed from its elements under standard conditions
• enthalpy change of formation for an element

  0 kJ mol -1

  there's no change when an element