Question

Calculate the enthalpy change for the ionization of sodium chloride given that the enthalpy of formation of NaCl is -411 kJ/mol, and the ionization energy of Na and Cl are 496 kJ/mol and 349 kJ/mol respectively.

Answer 1

To calculate the enthalpy change for the ionization of sodium chloride  NaCl , we need to consider the following reactions:1. Formation of NaCl from its elements:Na s  + 1/2 Cl2 g   NaCl s       Hf = -411 kJ/mol2. Ionization of Na:Na s   Na+ g  + e-      Hi Na  = 496 kJ/mol3. Electron affinity of Cl:1/2 Cl2 g  + e-  Cl- g       Hea Cl  = -349 kJ/molNow, we need to add the enthalpies of these reactions to find the overall enthalpy change for the ionization of NaCl:Hionization NaCl  = Hf NaCl  + Hi Na  + Hea Cl Hionization NaCl  = -411 kJ/mol + 496 kJ/mol - 349 kJ/molHionization NaCl  = 736 kJ/mol - 411 kJ/molHionization NaCl  = 325 kJ/molTherefore, the enthalpy change for the ionization of sodium chloride is 325 kJ/mol.