Chemistry · THERMODYNAMICS

Why is it impossible to determine the lattice enthalpy of an ionic crystal like \( \text{NaCl}(s) \) directly by experiment?

1. Because an isolated ionic solid cannot be vaporized directly into separated gaseous ions without supplying high thermal energy that triggers non-ionic decomposition.
2. Because standard states of sodium and chlorine are not gases under normal conditions.
3. Because the gaseous ions immediately condense back into solid before thermal changes can be measured.
4. Because the process involves non-stoichiometric electronic transitions.