energetics

• lattice enthalpy 


  The enthalpy change when one mole of an ionic compound is converted to gaseous ions.
• enthalpy of atomisation 


  The enthalpy change when one mole of gaseous atoms is formed from the element in its standard state.
• First electron affinity

  The enthalpy change when one mole of gaseous atoms is converted into gaseous ions with a single negative charge.
• standard enthalpy of formation 


  the enthalpy change when one mole of a compound is formed from its elements under standard conditions
• hess’s law

  the enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same
• 1st ionisation energy


  the energy required to convert one mole of gaseous atoms into one mole of gaseous ions with a single positive charge
• enthalpy of solution


  enthalpy change when one mole of a solute dissolves in water
• enthalpy of hydration


  enthalpy change when one mole of gaseous ions is converted to one mole of aqueous ions
• feasible 


  a reaction for which 🔺G > 0
• entropy 


  a measure of disorder (randomness)
• free energy change (🔺G)


  🔺G=🔺H-T🔺S
• which way should arrows point

  towards the products

  (up for formation)

  (down for combustion)
• what causes stronger ionic bonds

  smaller ion (more polarising)

  large charge difference
• how do you convert BDE to eoAt

  divide by 2

  (Cl2->2Cl2 /2 = 1/2Cl -> Cl)
• calculating lattice enthalpy

  F Latt = all that

  units and sign (KJmol-1)
• calculating enthalpy of solution

  s = latt + hyd +hyd

  
• for a reaction to be spontaneous/feasible DG must be

  negative (KJmol-1)
• is a reaction feasible if DS is negative and DH is positive?

  no

  DG will be positive
• is a reaction feasible if DS is positive and DH is negative?

  yes

  DG will be negative
• enthalpy of solution diagram

  .

  A) solution

  B) lattice enthalpy

  C) hydration

  D) hydration

  
• calculate minimum temperature where reaction is feasible

  T = DH/DS