BORN-HABER CYCLES.pptxq12239rhhjdshjjdhs

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1. BORN-HABER CYCLES Born-Haber cycle is another application of Hess’s law, used to show energy changes in the formation of an ionic compound. The steps in the cycle include Ionization Energy, Enthalpy of Atomization, Electron Affinity, Lattice Enthalpy, and Enthalpy of Formation

2. FIRST IONIZATION ENERGY Symbol : IE (1) ; ∆H ion1 ; ∆H ie1 The enthalpy change that occurs when one mole of gaseous atoms each loses one electron to form one mole of gaseous ions, each with a +1 charge. This will be positive (endothermic) Ex : Mg (g)  Mg + (g) + e -

3. SECOND IONIZATION ENERGY Symbol : IE (2) ; ∆H ion2 ; ∆H ie2 The enthalpy change that occurs when one mole of gaseous ions with a +1 charge each loses one electron to form one mole of gaseous ions, each with a +2 charge This will be positive (endothermic) Ex : Mg + (g)  Mg +2 (g) + e -

4. FIRST ELECTRON AFFINITY Symbol : EA (1) ; ∆H ea1 ; ∆H 1st ea The enthalpy change that occurs when one mole of gaseous atoms each gains one electron to form one mole of gaseous ions, each with a -1 charge. This will be negative (exothermic) Ex : O (g) + e -  O - (g)

5. SECOND ELECTRON AFFINITY Symbol : EA (2) ; ∆H ea2 ; ∆H 2nd ea The enthalpy change that occurs when one mole of gaseous ions with a -1 charge each gains one electron to form one mole of gaseous ions, each with a -2 charge This will be positive (endothermic) Ex : O - (g) + e -  O -2 (g)

6. ENTHALPY OF ATOMIZATION Symbol : ∆H at ; ∆ H atom The enthalpy change that occurs when one mole of gaseous atoms is formed from a substance in its standard state This will be positive (endothermic) Ex : Na (s)  Na (g)

7. LATTICE ENTHALPY Symbol : ∆ H lattice ; ∆H LE The enthalpy change that occurs when one mole of solid ionic lattice is formed from its constituent ions in the gas phase This will be positive (endothermic) Ex : Na + (g) + Cl - (g)  NaCl (s)

8. USING THE BORN-HABER CYCLE