How to compute specific surface energy for cubes of varying sizes?

[Guilty_Way6122]

Homework Statement

Compute the specific surface energy in J/g for a 1-gram cube of table salt with an edge of 0.77 cm, when it is split into
(a) 1 µm side cubes
(b) 1 nm side cubes
(c) 1nm radius sphere

Relevant Equations

NaCl: Surface energy, γ = 0.2 J/m^2 ; Edge energy, E = 3 x 10^-11 J/m

I got these values but I wanted to make sure I was doing it the correct way
a) 0.548 J/g for system of 1 µm cubes
b) 9.131 x 10^19 J/g for system of 1 nm cubes
c) 273.890 J/g for system of 1 nm radius spheres

 

[mjc123]

As you haven't shown us the way you're doing it, how can we tell if you're doing it the right way?
But compare the magnitudes of your numbers. Do you really expect 1 nm cubes and 1 nm spheres to be so different? Looks like something's wrong somewhere. Please show your working.