Question

The interaction energy between Na+ and Cl− ions in the NaCl crystal can be written as





 

 ×
+
×
= −
− −
8
4.03 10 28 6.97 10 96
( )
r r
E r where the energy is given in Joules per ion pair, and
the interionic separation r is in meters. Calculate the binding energy and the equilibrium ionic
separation in the crystal.