THE FACTORS AFFECTING THE STABILITY OF ADDITION COMPOUNDS IN SOLUTION AND THEIR INFLUENCE UPON IONIZATION EQUILIBRIA (Part I).1

James Kendall, Paul M. Gross
1921 Journal of the American Chemical Society  
It is unfortunate that any attempt to modify the currently accepted ionization theory inevitably introduces a great many complicating factors, especially when solutions of finite concentration are considered. Compound formation between solvent and solute, changes in molecular complexity of solvent and solute, complex ion formation, etc.-all these are influences about which so little is definitely known that it soon becomes impossible to treat the subject satisfactorily in a strictly
more » ... trictly quantitative manner. Before any real advances can be made toward a new and more comprehensive theory it will consequently be necessary to examine very closely the effect of these various factors upon the simple equilibrium postulated at present between "ionized" and "non-ionized" solute. Some preliminary steps in this direction have been made in earlier 1 This article was practically completed in 1917 (see Kendall, Booge and Andrews, THIS JOURNAL, 39,2303 (1917)) ; its publication has been delayed by the absence of both authors on war work and by the subsequent postponement of the additional experimental tests which it was desired to impose upon the views here put forward. The first section of this confirmatory experimental work is now presented in the succeeding article. In the interim, many investigators in this field have followed Milner, (PhiZ. Mug., 35,214 and 354 (1918)) and Ghosh ( J . Chem. SOC., 113,449 and 627 (1918)) in postulating complete ionization in'solutions of strong eleetrolytes. Mention may be made in particular of recent articles by A. A. Noyes and MacInnes (THIS JOURNAL,^^, 239 (1920)), and by Langmuir (ibid ., 42,287(1920) ). The whole question of the abnormality of strong electrolytes, as related to the ionization hypothesis advanced in this and previous papers, will be dealt with in detail in a subsequent article of this series, so that it would be premature to dwell upbn the matter a t this point. As may be gathered from the contents of this communication, however, the present authors are not in agreement with the fundamental assumption of Ghosh that the only equilibrium to be considered in a solution of a strong electrolyte Rx in water is the electrostatic equilibrium between simple "free" and "bound" ions R + and X-, but insist upon the additional necessity of taking into account the existence of solvent-solute complexes in all conducting solutions and their influence upon ionization. Inter-ionic attractive forces must undoubtedly be recognized in any final quantitative treatment of the problem, but no satisfactory sohtion can possibly be obtained if all other factors are totally neglected. I n this connection it may be profitable to repeat the opinion clearly expressed in a recent paper by Wells and Smith (THIS JOURNAL, 42, 185 (1920); see also previous articles by G. McP. Smith in ibid.,) that our failure to elucidate ionization equilibria has been mainly due to our refusal to take into account the occurrence of complex chemical reactions between the different ionic and molecular species in the solution. The factors affecting such reactions are further discussed in the present communication.
doi:10.1021/ja01440a005 fatcat:oiyw6f5whrg77beyz26sbtukf4