Thermodynamics

• Enthalpy of atomisation/ΔHatθ

  energy required for the formation of a mole of gaseous atoms under standard conditions
• Enthalpy of ionisation/ΔHiθ

  enthalpy change when you remove an electron from 1 mole of gaseous atoms
• Enthalpy of lattice formation/ΔHLFθ

  Energy needed to form an ionic lattice from its constituent ions in a gaseous state under standard conditions
• Enthalpy of lattice dissociation/ΔHLDθ

  The energy required to break apart an ionic lattice into it’s constituent ions in a gaseous state under standard conditions
• Enthalpy of electron affinity/ΔHeaθ

  The energy required for the formation of a mole of gaseous atoms under standard conditions
• Example of born-haber cycle for $MgF_2$

  
• Enthalpy of hydration/ΔHHydθ


  Enthalpy change when one mole of gaseous ions is dissolved in water to form one mole of aqueous ions under standard conditions.
• Enthalpy of solution/ΔHSolθ


  Enthalpy change when one mole of an ionic substance dissolves in water with all substances in standard conditions
• Enthalpy of solution cycle

  
• Perfect ionic model assumptions

  • Ions display no covalent character
  • ions are perfectly spherical
• What is covalent character 


  Occurs when two joined ions have varying sizes or charge ,so the distribution of charge isn’t even
• What is entropy (Δs)


  Measure of disorder of a system .

  The greater the disorder, the greater the entropy

  Its measured in JK-1mol-1
• $\Delta S\ =$$\ \Delta S\ products\ -\ \Delta S\ reac\tan ts$
• $\Delta G\ =$$\ \Delta H\ -\ T\Delta S$


  ΔG - Gibbs’s free energy (kjmol-1)

  ΔH - enthalpy changes (kjmol-1)

  T - temperature (k)

  ΔS - entropy (jk-1mol-1) *divide by 1000 to convert to kj
• Positive - not feasible

  Negative - feasible
• If temperature isn’t given


  T = ΔH/ΔS