Show that the surface area per unit mass, A,, of particles of density p is given by: A, = k’/pr…

Show that the surface area per unit mass, A,, of particles of density p is given by: A, = k'/pr where Y is some characteristic dimension, and k' = 3 for spheres, 2 for thin cylindrical discs and long rods, and 4 for long square prisms. (Am is called the specific surface area and typical values for a colloidal material fall in the range 1-lo3 m2 g-I.1