Fajans

Fajans method The titration of Cl" with Ag using fluorescein as an adsorption indicator. At the end point the precipitate becomes red. 

Fajans rules Ionic compounds are most readily formed by ... 

Stem layer adsorption was involved in the discussion of the effect of ions on f potentials (Section V-6), electrocapillary behavior (Section V-7), and electrode potentials (Section V-8) and enters into the effect of electrolytes on charged monolayers (Section XV-6). More speciflcally, this type of behavior occurs in the adsorption of electrolytes by ionic crystals. A large amount of wotk of this type has been done, partly because of the importance of such effects on the purity of precipitates of analytical interest and partly because of the role of such adsorption in coagulation and other colloid chemical processes. Early studies include those by Weiser [157], by Paneth, Hahn, and Fajans [158], and by Kolthoff and co-workers [159], A recent calorimetric study of proton adsorption by Lyklema and co-workers [160] supports a new thermodynamic analysis of double-layer formation. A recent example of this is found in a study... 

See K. Fajans, Radio Elements and Isotopes. Chemical Forces and Optical Properties of Substances, McGraw-Hill, New York, 1931. 

Investigations to find such additive constituent properties of molecules go back to the 1920s and 1930s with work by Fajans [6] and others. In the 1940s and 1950s lhe focus had shifted to the estimation of thermodynamic properties of molecules such as heat of formation, AHf, entropy S°, and heat capacity, C°. 

A 0.1036-g sample containing only BaCl2 and NaCl is dissolved in 50 ml of distilled water. Titrating with 0.07916 M AgN03 requires 19.46 ml to reach the Fajans end point. Report the %w/w BaCl2 in the sample. 

Faience Failure analysis Fair-Plus Fajans method Falcon... 

A number of trends connected with ionic radii are noticeable across the series. In keeping with Fajans rules, salts become somewhat less ionic as the Ln " radius decreases reduced ionic character in the hydroxide implies a reduction in basic properties and, at the end of the series, Yb(OH)3 and Lu(OH)3, though undoubtedly mainly basic, can with difficulty be made to dissolve in hot cone NaOH. Paralleling this change, the [Ln(H20)j ] + ions are subject to an increasing tendency to hydrolyse, and hydrolysis can only be prevented by use of increasingly acidic solutions. 

The much rarer element, protactinium, was not found until 1913 when K. Fajans and O. Gohring identified Pa as an unstable member of the decay series ... 

No extensive comparison with experiment to test the values in Table IV will be made. The close agreement between the purely theoretical and the experimental results in the case of helium and neon allows one to place confidence in the R values for ions with these structures and the same remark applies with less force in the case of the argon structure, where only a small empirical correction was introduced. It is interesting to note that the theoretical values 3-57 and 6-15 for the rubidium and the caesium ion agree very well with the experimental ones, 3-56 and 6-17 (Table III), which were not used at all in the evaluation of the empirical corrections for these structures. Finally, we may mention that our values agree in general with those of Fajans and WulfE.i obtained by them from the experimental R values for salt solutions by the application of only the simplest theoretical considerations. 

Fajans and Wulff, not yet published. Their ionic refraction values for light of infinite wave-length are found by the methods applied by Fajans and Joos to the refraction for the sodium D-lines. 

Haber-Fajans cycle, e.g., for the standard hydrogen electrode in the... 

Fajans K (1913) Radioactive transformations and the periodic system of the elements. Berichte der Dautschen Chemischen Gesellschaft 46 422-439... 

Fajans K, Gohring O (1913) Uber die komplexe Natur des UrX. Naturwissenschaften 1 339 Ramsay W, Soddy F (1903) Experiments in radioactivity and the production of helium from radium. Proc R Soc London 72 204-207... 

The various U series were by now all but complete. Branched decays were understood, and a daughter of U-X was discovered— " Pa as it is now known, but initially named brevium to reflect it s short half-life (Fajans and Gohring 1913). By 1913, a published decay series (Fajans 1913) was remarkably close to that in use today, differing only in the absence of some of the branched decays after Ra-A ( Po), and in the precise values of some of the half-lives ... 

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