about perpendicular to the surface, this misorientation causes an additional
decrease in growth rate. This may be the main reason why triglyceride
crystals tend to be rather flat platelets, since the molecules in the crystal are
about perpendicular to the largest, i.e., the slowest growing, faces.Desolvation. As discussed in Section 3.2, solute molecules or ions
can be solvated, which means that one or more solvent molecules are
associated with the solute. This is especially true for ions or ionized groups
in aqueous solutions; the solvation (in this case hydration) then is due to
ion–dipole interactions, which are fairly strong, particularly for positive
groups (cations). Before an ion can be incorporated into a crystal lattice,
desolvation has to occur. This implies a temporary increase in free energy,
causing an activation barrier for crystallization. This will slow down the
crystallization rate.FIGURE15.9 Rate of growth and dissolutionLCof a certain crystal face of ab-
crystal of trilaurin in triglyceride oil as a function of supersaturation (lnb). (After
results by W. Skoda, M. van den Tempel. J. Crystal Growth 1 (1967) 207.