?(a) Use the Born-Mayer equation for the lattice enthalpy and a BornHaber cycle to

Chapter 15, Problem P15C.8

(choose chapter or problem)

(a) Use the Born-Mayer equation for the lattice enthalpy and a BornHaber cycle to estimate the enthalpy of formation of CaCl(s). The sublimation enthalpy of Ca(s) is \(176 \mathrm{~kJ} \mathrm{~mol}^{-1}\) and it can be assumed that the ionic radius of \(\mathrm{Ca}^{+}\) is close to that of \(\mathrm{K}^{+}\); other necessary data are to be found in Example 15 C. 2 or in the tables in the Resource section.

(b) Show that an explanation for the nonexistence of CaCl(s) can be found in the reaction enthalpy for the disproportionation reaction \(2 \mathrm{CaCl}(\mathrm{s}) \rightarrow \mathrm{Ca}(\mathrm{s})+\mathrm{CaCl}_{2}(\mathrm{~s})\).

Text Transcription:

176 kJ mol^-1

Ca^+

K^+

2 CaCl(s) rightarrow Ca(s)+CaCl_2(s)