question_answer 1)

  The lattice enthalpy of an ionic compound is the enthalpy when one mole of an ionic compound present in its gaseous state, dissociates into its ions. It is impossible to determine it directly by experiment. Suggest and explain an indirect method to measure lattice enthalpy of\[NaCl(s)\].

Answer:

  Lattice enthalpy of \[NaCI\]can be determined by using Born Haber Cycle     On applying Hess's law: \[{{\Delta }_{f}}H=\Delta {{H}_{sub}}+\frac{1}{2}\Delta {{H}_{diss.}}+{{\Delta }_{ie}}H+{{\Delta }_{eg}}H\]                \[+\Delta {{H}_{lattice}}\] using above relation we can calculate lattice enthalpy.