Calculate the energy for vacancy formation in silver, given that the equilibrium number of vacancies at 800oC (1073 K) is 3.6 X 1023 m-3. The atomic weight and density (at 800oC) for silver are, respectively, 107.9 g/mol and 9.5 g/cm3. (Avogadro's Number = 6.023 X 1023)