I understand that the lattice energy is the energy released when a crystal forms and that's the reason it takes the negative sign. But do we need to add this energy again when we are trying to vaporize an ionic compound ?
For example, let's assume we want to completely vaporize a mole of NaCl starting at room temperature, how much energy do we need ?
I don't know neither the specific heat nor the latent heat of vaporization of NaCl, but I understand we would need:
1- Energy to raise the temperature of mole of NaCl from 298 °K to its boiling point.
2- Energy equal to the latent heat of vaporization of a mole of NaCl.
I don't know whether NaCl would go through the liquid state or not, but if it does then we would need to add the latent heat of fusion too.
Now, according to wikipedia, NaCl has a lattice energy of −756 kJ/mol. So my question here is: do we need to add this lattice energy to the calculated steps above to account for all the energy required to vaporize a mole of NaCl ?