Equation to Account Quantitatively for the Variation of Apparent Molal Volume of Strong Electrolytes in Solution According to Cube Root of Concentration

University College of Science and Technology, Calcutta-700 009

Manuscript received 25 March 1983, revised 21 September 1983, accepted 11 February 1984

From a consideration of the chemical potential of the ions of a strong electrolyte dissolved in water it has been found that k (kappa) of the Debye.Huckel theory requires modification. Further theoretical considerations have led to the conclusion that the modified kappa, denoted by k_m, should vary with dilution according to cube-root of concentration. Equations deduced by using this k_m show that partial molal volume and apparent molal volume of a strong electrolyte in solution should vary with dilution according to cube root of concentration. The equation for the apparent molal volume bas been subjected to test using the data available in the literature on NaCI, KCI, NaBr, NH₄N0₂, Na₂S0₄ and SrCI₂ and has been found satisfactory.