A GENERAL SHRINKING-PARTICLE MODEL FOR THE CHEMICAL DISSOLUTION OF CRYSTALLINE FORMS

When actual solid systems are observed, be they organic, inorganic or mineral solids, all appear to have non-isometric crystalline and defin ed shapes. In this paper a general procedure for modelling the dissolu tion of any shape of crystalline solid in a chemical control regime is presented. The general equations are deduced for a triclinic prism, a body of the least symmetry, and are applicable to all bodies of the s even fundamental crystalline systems as particular cases. For simplici ty, a radius of a kinetic sphere is defined and the relations between the radius and the fraction reacted are given to make it possible to f ollow chemically the reaction for all bodies of the seven crystalline systems. The influence of external shape (angles between faces and edg es) and area of the surface/volume ratio in the kinetic behaviour are discussed.