(a) The ionization energy of potassium (K) is 4.34 eV and the electron affinity of chlorine (Cl) is -3.61 eV. The Madelung constant for the KCl structure is 1.748 and the distance between ions of opposite sign is 0.314 nm. On the basis of these data only, compute the cohesive energy of KCl per ion pair. (b) The observed cohesive energy of KCl is 6.42 eV per ion pair. On theassumption that the difference between this figure and that obtained in (a) is due to the exclusion principle repulsion, find the exponent n in the formula Br^-n for the potential energy arising from this source.

(a) The ionization energy of potassium (K) is 4.34 eV and the electron affinity of chlorine (Cl) is -3.61 eV. The Madelung constant for the KCl structure is 1.748 and the distance between ions of opposite sign is 0.314 nm. On the basis of these data only, compute the cohesive energy of KCl per ion pair. (b) The observed cohesive energy of KCl is 6.42 eV per ion pair. On theassumption that the difference between this figure and that obtained in (a) is due to the exclusion principle repulsion, find the exponent n in the formula Br^-n for the potential energy arising from this source.

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter19: The Chemistry Of The Main-group Elements

Section: Chapter Questions

Problem 96QRT: Use a Born-Haber cycle (Sec. 5-13) to calculate the lattice energy of MgF2 using these thermodynamic...

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