Calculate the change in interaction potential in dissolving a MgCl2 salt crystal

Using magnesium chloride salt as your reference, calculate the following. Some useful information: Ionic radii: Mg2+= 86 pm, Cl- = 167 pm, liquid water dipole =2.95 D, water radius 140 pm, assume that Mg2+ and Cl– are each hydrated
by 6 waters (octahedral) and assume that the εr = 1 (even though you are using water, there are no waters between the dipole and the ion, thus the vacuum relative permittivity).
(a) Calculate the change in interaction potential in dissolving a MgCl2 salt crystal in water. Treat the MgCl2 crystal as containing non-interacting “blocks” of MgCl2 that are packed together to form a crystal, that is for the purposes of this exercise we will assume that each Mg2+ interacts with just 2 Cl– and each Cl– interacts with just 1 Mg2+).
(b) With reference to your answer to part (a), explain why MgCl2 dissolves in water.