Exercise 5 The net potential energy between two adjacent ions, U, may be represented by the sum in the following equation: U=+ a, b, and n are constants. a) Derive the expression of bonding energy U. in terms of the parameters a, b, and n. b) Calculate the equilibrium interionic spacing ro for sodium iodide crystal. Knowing that the bond energy is 669.5x10 kJ/kmol, the Madelung constant 1.75 and n-9.5