It is well known that common salt (NaCl) is easily dissoved in water. In the solution Na and Cl atoms are present as positive and negative ions. show that, due to high dielectric constant of water the resulting screening of the coulomb potential, the binding energy of NaCl crystal in water is smaller than the mean thermal energy of the free ions. Calculate the equilibrium separation of the ions of a hypothetical NaCl crystal in water and show the separation is larger than the van der waals radius of a water molecule to justify the solubility of NaCl