Cohesion energy lattice enthalpy

The cohesion of the atoms of a crystal lattice is determined by the energy that holds the atoms together and which is released when the crystal is disassembled into its atomic, molecular, or ionic components. It will be called the lattice energy or lattice enthalpy... 

Table 1.10 The lattice energies f/iat (at 0 K), cohesive energies, Vs s (at T = I.ITf) and the sums of the standard molar enthalpies of hydration of the constituent ions — (at 298.15...

In the simplest analysis, an entropy increase favours dissolution, due to the dissociation of the crystal into the maximum number of independent particles. The main differences in solubility in various solvent/salt combinations reflect differences in the lattice enthalpy of the salt, cohesive enthalpy of the solvent and the solvation enthalpy. Conditions which favour dissolution are (i) a low lattice energy of the salt (ii) a low cohesive energy of the polymer and (hi) a high solvation energy. 

Fig. 5.3. Lattice potential in displacement of a CH2 group in crystalline and amorphous polyethylene (after 1221). Ucoh = cohesive energy per CH2 in PE crystal, AUtt = potential maximum in twisted translation, Ham, 0 enthalpy of PE crystal at 0 K, Ham def = difference of enthalpies of undeformed and deformed amorphous phase of PE.

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