Thermodynamics

• Using Hess's law

  • So gaseous ions Na+(g) and Cl-(g) can either form an ionic compound NaCl which would the give enthalpy of lattice of formation
  • Or they form hydrated ions Na+(aq) and Cl-(aq) which would give the enthalpy of hydration
  • And NaCl can form hydrated ions this would give the enthalpy of solution

  
• ∆S = S(products) - S(reactants)

  More positive entropy change = more disorder
• Gibb's free energy ∆G = ∆H -T∆S

  ∆G is Gibbs free energy

  ∆H is the enthalpy change is J/mol

  T is temperature in Kelvin

  ∆S is the entropy change measured J/K/mol