Electrostatic Lattice Energy of PbSO4, BaSO4, SrSO4 and CaSO4

A plan for investigation of the physical chemistry of radical ions is stated with especial reference to the strict treatment of the lattice energy problem and the treatment of complex ionic crystals. First, the expressions suitable for the practical numerical calculation of Madelung’s coefficient of the general and the rectangular crystal lattice are derived from Ewald’s original general expressions. Next, they are verified in the two simple cases, NaCl and the rhombic CaCO3, by means of numerical application. Then, they are applied to the more complex cases, i. e., the rhombic crystals of PbSO4, BaSO4, SrSO4, and CaSO4, with SO4−− which is assumed to be a point charge. The degree of accuracy of the calculated values is further discussed; and, in connection with it, an attempt is made to estimate the extent of variability of Madelung’s “ coefficient” (or “constant,” as it is called). Finally, the electrostatic lattice energy is evaluated.