Crystals Energetics
Solution calorimetry can be used, for example, to study i) the lattice energy between polymorphs or ii) the enthalpic difference of salts or co-crystals relative to its precursors.
The lattice energy difference between two solid phases can be accurately obtained from the enthalpy of solution of the polymorphs in a given solvent to give a solution with the exact same concentration [1]:
In turn, the enthalpy variation associated with the formation of salts or co-crystal relative to its precursors:
is obtained by comparison of the enthalpy of solution of the complex material, with that found from the raw materials to give a solution with the same composition, i.e.:
so that:
From the relations above is possible to discuss the stability of the composite material from enthalpic grounds, or obtain the enthalpy of formation of the salt/co-crystal, if the enthalpy of formation of A and B are known [2].