THE THEORETICAL GROWTH FORM OF POTASSIUM-NITRATE FROM AN AQUEOUS-SOLUTION

The theoretical growth form the potassium nitrate, obtained from a PBC analysis, is compared to the growth forms obtained from aqueous solutions. The discrepancies are explained satisfactorily in a semi-quantitative way by taking the solvent interaction into account. It was assumed that the desolvation of the crystal surface determines the growth rate. The solvent interaction was obtained from molecular mechanics calculations on water molecules at the solvent accessible surfaces of the crystal faces. It was observed that the water molecules orient preferentially with their dipole moments parallel to the surface to form a "skin", kept together by hydrogen bonds.