Frans_M_Everaerts_Isotachophoresis_378342.pdf

40 CONCEPT OF MOBILITY
3.5.3. Discussion
In this section, some approaches for the estimation of ionic mobilities have been
considered. A different approach was used by Lindemann [ 1 51, based on the kinetic
theory of gases, in which the ions are supposed to suffer repeated collisions with solvent
molecules, at each of which it retains a certain fraction of its velocity depending on the
relative mass. Between collisions, it moves freely under the influence of the electric field.
A relationship is thus established between the mobility of the ion and its mean free path
between collisions.
Although some effects that affect the effective mobility can be described mathematically
and although the ionic mobilities can be treated theoretically from data such as entropy
and Stokes' law, the estimation of mobilities in practice is difficult. The mathematical
models cannot be applied to all ionic species and specific interactions give differences
between experimental and theoretical values, especially when non-aqueous solvents are
used. Experimental measurements often have to be carried out for the determination of
the ionic mobilities.
REFERENCES
1 H. Falkenhagen, Elektrolyte, Verlag von S. Hirzel, Leipzig, 1932.
2 A. Tisellus, Nova Acta Regiae soc. Sci. Upsal., Ser. 4, 4 (1930) 7.
3 J.T. Edward, Advan. Chrornutogr., 2 (1 966) 64.
4 P.V. Chengand H.K. Schachrnan, J. Polym. Sci., 16 (1955) 19.
5 W. Weidel and E. Kellenberger, Biochim Biophys. Acru, 17 (1955) 1.
6 J.T. Edward, J. Polym. Sci., 25 (1957) 483.
7 J.T. Edward, Chcm Ind (London), (1956) 714.
8 J.T. Edward, Sci. Proc. Rqv. Dublin Soc., 9 (1956) 273.
9 A. Bondi,J. Phys. Chem, 68 (1964) 441.
10 L. Pauling, Nature sf'thc Chtmical Bond, Cornell Univ. Press, Ithaca, N.Y., 2nd. ed., 1948.
11 F. Perrin, J. Phys. Radium, 7 (1936) 1; 5 (1934) 497.
12 J.T. Edward and D. Waldran-Edward, J. Chromarogr., 24 (1966) 125.
13 E.K. Zolotarev, Russ. J. Phys. Chcnz., 39 (1965) 573.
14 A.F. Kapustinskii, Acfu Physicochim. URSS, 14 (1941) 508.
15 F.A. Lindemann, 2. Phys. Chem (Leipzig], 11 0 (1924) 394.