[150] Students will not be capable of following the argument given in the succeeding passages and would better omit this part until Chapter XV has been studied.
[151] Kablukoff, Z. phys. Chem., 4, 430 (1889). See also Nernst, Theoretical Chemistry, p. 373.
[152] In view of the low order of accuracy of the data, and of the approximate method of calculation, this result is only qualitative, but even with an error of 102 to 104 the argument in the text would hold.
[153] For hydrogen under atmospheric pressure, the equilibrium ratio, [Zn2+] / [H+]2, is, approximately, 1027.
[154] Vide Sackur, Z. Elektrochem., 11, 387 (1905). Kahlenberg holds a different view; ibid.
[155] The negative results obtained with aluminium and magnesium are possibly more interesting than the positive action observed with zinc, but their inactivity may be due to thin films of protective chloride or oxide or to a passive condition (vide Smith's Inorganic Chemistry, pp. 723, 753; College Chemistry, p. 475).
[156] The work of Ostwald, Arrhenius, Nernst and many others shows conclusively that the liberation of hydrogen by metals and the precipitation of metals by one another is a function of ion concentrations (Chapter XIV). Vide Nernst, Theoretische Chemie (1905), p. 245.
[157] See above.
[158] In a 0.1 molar solution of potassium cyanide, the potassium hydroxide formed by the decomposition of the cyanide by water is approximately 0.0013 molar and the concentration of hydrogen-ion is reduced to 10−11 (Chapter X), a value roughly of the same order as that calculated above as a possible concentration of hydrogen-ion in a benzene solution of hydrogen chloride. In spite of this small concentration of hydrogen-ion in the cyanide solution, the reactions in which it is involved are, as far as known, completed in a few moments. Only for much smaller concentrations of ions have any doubts as to their direct action been aroused; in Chapter XII this question, as raised by Haber, is discussed for concentrations of ions of the order of 10−23. Haber considers that ionic concentrations of 10−14 can still account for very fast actions.
[159] Cf. Abegg., Theorie der Elektrolytischen Dissociation (1903), 255; Lehfeldt, Electro-chemistry (1904), 87.