Chapter 2, Problem 4P

The electron affinity of Cl is 3.89 eV and the ionization energy of K is 4.34 eV. Use the preceding problem to find the dissociation energy. (Neglect the energy of repulsion.)

In this problem you will model the mixing energy of a mixture in a relatively simple way, in order to relate the existence of a solubility gap to molecular behavior. Consider a mixture of A and B molecules that is ideal in every way but one: The potential energy due to the interaction of neighboring molecules depends upon whether the molecules are like or unlike. Let n be the average number of nearest neighbors of any given molecule (perhaps 6 or 8 or 10). Let Uo be the average potential energy associated with the interaction between neighboring molecules that are the same (A-A or B-B), and let UAB be the potential energy associated with the interaction of a neighboring unlike pair (A-B). There are no interactions beyond the range of the nearest neighbors; the values of Uo and UAB are independent of the amounts of A and B; and the entropy of mixing is the same as for an ideal solution. Find a formula for the total potential energy when the system is mixed, in terms of x, the fraction…

Why do molecular compounds have low melting and boiling points compared to ionic compounds?