enthalpy change

• enthalpy change = exchange of energy between reactions and surroundings during a reaction
• bond enthalpy = enthalpy change required to break one mole of bonds in gaseous molecules. measured in kJ/mol.
• BENDOMEX

  • bond Breaking is an ENDOthermic process
  • bond Making is an EXothermic process
• activation energy = minimum energy required for a reaction to take place
• exothermic reactions = energy is lost to surroundings so they have a negative enthalpy change
• endothermic reaction = energy is taken in from the surrounding so have a positive enthalpy change
• enthalpy change of neutralisation = enthalpy change when 1 mole of water is formed in a reaction between an acid and a base
• enthalpy change of combustion = enthalpy change when one mole of a substance (reactant) is completely burned in excess oxygen
• enthalpy change of formation = enthalpy change associated with 1 mole of substance being formed from its element under standard conditions with all of the products and reactants in their standard states
• enthalpy change of reaction - enthalpy change when a reaction takes place under standard conditions
• calorimetry

  • fuel is burned to raise the temp of water by a specific amount
  • weigh fuel before and after to work out mass burn burnt off
  • can work out enthalpy change using q=mcΔt
• enthalpy change = total energy taken in to make bonds - total energy to break bonds