Kapustinskii equation - Alchetron, The Free Social Encyclopedia

The Kapustinskii equation calculates the lattice energy U_L for an ionic crystal, which is experimentally difficult to determine. It is named after Anatoli Fedorovich Kapustinskii who published the formula in 1956.

U L = K ⋅ ν ⋅ | z + | ⋅ | z − | r + + r − ⋅ ( 1 − d r + + r − )

The calculated lattice energy gives a good estimation; the real value differs in most cases by less than 5%.

Furthermore, one is able to determine the ionic radii (or more properly, the thermochemical radius) using the Kapustinskii equation when the lattice energy is known. This is useful for rather complex ions like sulfate (SO2−
4) or phosphate (PO3−
4).

Literature

A. F. Kapustinskii; Z. Phys. Chem. Abt. B Nr. 22, 1933, pp. 257 ff.

A. F. Kapustinskii; Zhur. Fiz. Khim. Nr. 5, 1943, pp. 59 ff.

A. F. Kapustinskii: Lattice energy of ionic crystals. In: Quart. Rev. Chem. Soc. Nr. 10, 1956, pp. 283–294. doi:10.1039/QR9561000283

References

Kapustinskii equation Wikipedia

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