Thermodynamics defenitions

• Enthalpy of formation

  enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions (298 K and 100 kpa),

  Na (s) + ½Cl2 (g) NaCl (s) 
• Enthalpy of atomisation

  enthalpy change when 1 mole of gaseous atoms is formed from the element in its

  standard state

  Na (s) Na(g)

  ½ O2 (g) O (g)
• Bond dissociation enthalpy

  the standard molar enthalpy change

  when one mole of a covalent bond is broken into two gaseous

  atoms (or free radicals)

  Cl2 (g) 2Cl (g) 
• First ionisation energy

  enthalpy required to remove one mole of electrons from one mole of atoms in the gaseous state

  Mg (g) to Mg+ (g) + e-
• First electron affinity

  enthalpy required when one mole of gaseous atoms gain one mole of electrons

  O (g) + e- forms O- (g)
• Enthalpy of lattice formation

  enthalpy change when one mole of an ionic solid is formed from its gaseous ions

  Na+ (g) + Cl- (g) NaCl (s) 
• Enthalpy of lattice dissociation

  enthalpy change when one mole of an ionic solid is transformed into its gaseous ions

  NaCl (s) Na+ (g) + Cl- (g)
• Enthalpy of hydration

  Enthalpy change when one mole of gaseous ions become aqueous ions.

  X+(g) + aq X+(aq)
• Enthalpy of solution

  enthalpy change when one mole of an ionic solid dissolves in a large enough amount of water to ensure that the dissolved ions are well separated and do not interact with one another.

  NaCl (s) + aq Na+ (aq) + Cl-(aq)