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The adsorption of the surfactant 14C-hexadecyltrimethylammonium ion at the air-water interface was measured directly by detecting radioactivity emitted by adsorbed molecules. This was accomplished by placing a gas flow detector above the surface containing surfactant of known specific activity. Adsorption in the presence of potassium halide ions was found to change in the order bromide > chloride > fluoride, indicating specific ion interactions at the surface. Tetraalkylammonium halides produced the same order of effect for halide ions, but an inhibitory effect on adsorption was noted with increasing alkyl chain length. This effect appears to be related to their salting-in properties. Large hydrophobic anions, such as some alkyl- and arylsulfonates, produce two effects, depending on the concentration of surfactant and sulfonate. Ion association at the surface occurs at low sulfonate concentrations, whereas at higher sulfonate concentrations the ion association in bulk solution occurs, leading to less adsorption.

Homologous anionic surfactants may be separated from each other by solvent extraction of their ion-association compounds with iron(II) chelates. Separations of components from a number of surfactant mixtures were investigated, and the effect of solution variables on extraction and separation was studied. A method is proposed for the determination of surfactants of various chain lengths. Applications of this method to synthetic mixtures and to biodegradation experiments are described.

Thermodynamic quantities have been obtained for the formation of the ion pairs Ca2+Fe(CN)64- and Ca2+Fe(CN)63- in dilute aqueous solution by a potentiometric method employing an ion-exchange (Orion) calcium electrode. The reversibility of the electrode was examined against calomel and silver chloride references and was further tested in a determination of the formation constant for CaSO4 (aq). The mean enthalpies of ion association of calcium with both hexacyanoferrates were obtained from the temperature variation of equilibrium constants within the range 15 to 35°C. The enthalpies were also independently determined calorimetrically. The results, discussed in terms of the electrostatic model, suggest that there is little penetration, if any, of hydration shells in the ion pairs.

The ion-association model of Berner has been extended to calculate the contributions of the various ion-pair formation reactions to the buffer capacity of the carbon dioxide system in seawater. These reactions are shown to make the major contribution to the equilibriunz buffer capacity at pH values greater’ than 8. However the indifference of the pH to quite large changes in solution composition arises, not from any pH-statting effect, but because the metal-carbonate ion-pairs form only a small proportion of the total cation concentration under normal conditions. Wangersky (1972a) has suggested that the buffer capacity of the carbon dioxide system in seawater is significantly influenced by the existence of a network of ionic interactions that can be conveniently described in terms of an ion-association model (e.g. Garrels and Thompson 1962). In particular he stated that The existence of ion pairing in such proportions suggests that reactions linking the CO:! system with each of the major ions in seawater must be considered as taking part in the control of seawater pH. [Wangersky 1972a, p. 21 If control of pH in seawater occurs through this whole web of equilibria, a change in the proportions of the major elements in seawater should lead to a change in ion pairing and finally to a change in pH. [Wangersky 1972a, p. 31 Here I propose to use an extended ionassociation model to look, in a quantitative manner, at the buffer capacity of the carbon dioxide system in seawater under equilibrium conditions to test this hypothesis and to see how far it is possible to explain Wangersky’s observations in terms of a conventional ion-pairing approach. I am concerned in this instance with a precise analysis of the role of ion-pairing in the buffering of the carbon dioxide system at equilibrium and not with the relative importance of the complementary buffer mechanisms described by Pytkowicz (1967) and Sillr Pytkowicz 1972) in describing the carbon dioxide system is not considered here. Ion-association model The ion-association model takes as its starting point values of the thermodynamic formation constants ( KB) of ion pairs thought to be formed in the solution. The free activity coefficients (fx) of the various components are then calculated on the basis of some hypothesis (Whitfield 1973a) and the corresponding stoichiometric constants ( K+ = =‘f~fx/fux) are used to describe the individual equilibria.

The following ion-association systems were investigated spectrophotometrically: Fe(2,2′-bipyridyl) 3 (Methyl Orange) 2 ; Fe(1,10-phenanthroline) 3 (Methyl Orange) 2 ; Fe(4,7-diphenyl-1,10-phenanthroline) 3 (Methyl Orange)2; Fe(1,10-phenanthroline) 3 (Benzyl Orange)2; Fe(4,7-diphenyl-1,10-phenanthroline) 3 (Benzyl Orange) 2 . The molar absorptivities may be calculated with good precision on the basis of the spectra of the reacting species (iron chelate and dye anion), their stoichiometry and the degree of extraction. Analytically the most useful is the Fe(1,10-phenanthroline) 3 (Methyl Orange) 2 complex, molar absorptivity 4·83 × 10 4 1. mole −1 cm −1 at 420 nm, but many metals (Co, Cu, Ni, Zn, Cd) form similar extractable complexes and interfere.

On the basis of the obstruction to ionic conduction by floating insulator bodies, an equation has been derived. The validity of this conductance equation has been established using experimental results from various sources. The extents of hydration of proteins and sucrose have been evaluated from this equation. This, and a suitably rearranged Fricke's equation help to calculate the axial ratios of the biopolymers. The possibility of ion association with the non-electrolyte may offer an increased hydration than that is usual.

Raman spectra of nitrate solutions and water subjected to low intensity electric fields with frequency up to 500 MHz have been recorded. No effect on the degree of ion association or on the shapes of Raman spectral lines of nitrate ion or water were observed but a small intensity change was observed for chloroform solutions. Magnetic fields of 12100 G similarly had no effect. Infrared spectra of water subjected to magnetic fields failed to show the intensity enhancement reported by Russain workers.

From studies of the specific hydroxide ion catalyzed decomposition of diacetone alcohol by dimethylthallium(III) hydroxide at 25°C, it is concluded that both ion pairs (dissociation constantK=0.090 mole-dm−3) and dimers (dimerization constantKd=1.5 dm3-mole−1) exist in aqueous solution.

Five nonaqueous binary solvent systems are described. Each system is composed of a polar and a nonpolar component, both of which are inert and do not exhibit leveling effects. The dielectric constant of each system is related to the composition of the polar component expressed as mole fraction, percent weight by weight and volume by volume. Consequently, it is possible to prepare a solvent mixture with a specific dielectric constant within the range of values of dielectric constant provided by the system. The formulas relating dielectric constant to the particular expression of the composition of the polar component are reported.

The electrical conductance of solutions of hydrochloric acid in a mixture of 80 wt% 2-methoxy-ethanol and 20 wt% water has been studied at temperatures from 20 to 50°C. The results have been interpreted with the Fuoss Onsager theory for associated 1-1 types electrolytes. The values of the association constant K A , the limiting conductivity and the distance parameters have been computed at each temperature.

The association constants of CsCl in water-THF, water-dioxane, and water-1,2-DME mixtures have been evaluated from conductance data using the Pitts, the Fuoss-Hsia, and a new conductance equation which includes the Chen electrophoretic effect. It is shown that the three sets of results confirm the Bjerrum concept of association. The differences observed for the ion association in the three types of mixtures are interpreted in terms of differences in the dipolar nature of the three organic molecules and that of H2O.

Conductivity of cadmium acetate over the concentration range of 10−4 to 10−3M was measured at 25°C. The approximate dissociation constant of CdAc2 in dilute aqueous solution was estimated from the relation, α=[Λ−36.5+39√C(1+2α)]/[57.9−93√C(1+2α)]. The limiting value of log10K for the association constant of CdAc+ ion was evaluated to be 1.75 at 25°C.

Summary The association energy between silver and chromate ions in molten alkali nitrates has been determined from e.m.f. measurements. The results agree with the predictions of the quasi-lattice model for ternary and quaternary reciprocal systems.

The isomerisation and anation reactions of complexes of the type trans-[CrCl(DMSO)(en)2]2+ and cis and trans-[Cr(DMSO)2(en)2]3+ have been studied in dimethyl sulphoxide (DMSO) over a wide range of chloride concentration and temperature. This work supplements an earlier study1 of the reactions of cis and trans-[CrCl2(en)2]+ in DMSO. Following the isolation of the trans-[CrCl(DMSO)(en)2](ClO4)2 complex a reappraisal of the previously suggested mechanism for the reactions of trans-[CrCl2(en)2]+ has been made. The kinetics were interpreted in items of a dissociative mechanism with the characteristic effects of ion association. For trans-[CrCl(DMSO)(en)2]2+ in the presence of chloride ion loss of ethylenediamine dominated the kinetics. However no significant loss of ethylenediamine was detected in any of the other reactions.

The anation by Cl−, Br−, and SO42− of the complex ion [Rh(NH3)5OH2]3+ has been kinetically studied at 65°C, in water solutions of controlled ionic strength. The reactions with Cl− and Br− were complete while a definite equilibrium was reached with SO42− in the sulfate concentration range 0.05–1.33 M. In the latter case equilibrium measurements were carried out in order to separate the observed rate constants into the aquation (kaq) and anation (kan) rate constants. In all cases kan was found to follow the equation kan = K . K a [X m− ] 1 + K a [X m− ] (Xm− = anion) consistent with a mechanism involving a fast 1:1 ion association (Ka being the «conditional» equilibrium constant) followed by a slow interchange of the water and the anionic ligands (k being the rate constant of this process). The comparison of k values with the water exchange rate constant ke of the aquo-complex under comparable conditions, (k/ke≥1), suggests for the interchange process a transition state where the incoming anion is appreciably bonded to the metal. Complications, possibly due to medium effects, were observed in the reaction with SO42−.

This paper interprets some of the complex energy transducing reactions of lipoprotein biochemical membranes in terms of macromolecular science. The processes considered involve ion (or electron)-exchange membrane reactions. Dilation of the membrane through osmosis and electrostatic repulsion at the exchange sites are opposed by a contraction which is postulated to arise from the presence of rubber like lipid bilayers. A change in the elasticity of the membrane alters the dilation-contraction equilibrium and modifies the ion interaction energies at the exchange sites. The elasticity is regulated by swelling interactions of the bilipids with control substances and, in some systems, by reversible cross-linking reactions. The latter can involve thioester cross-links, formed in reversible reactions with ATP, or various types of salt-links formed in association with ion concentration gradients across the membrane. Energized formation of the cross-links can oppose the dilation and change the ion selecti...

An examination has been made for the fluorescence of simple bromo-ion association complexes in hydrobromic acid glasses at –196° C. Strong fluorescence was observed for Sb(III), Sb(V), As(III), As(V), Bi, Ce(III), Pb, Tl(I), Sn(II) and U(VI), and the effects of variables such as hydrobromic acid molarity, time of irradiation, relationship between fluorescence intensity and metal-ion concentration were studied. With a standard commercial spectrofluorimeter with a slightly modified sample cell, these ions could be detected in hydrobromic acid at concentrations varying from 10–5 to 10–8M. Copper(I) and tellurium(IV) also exhibit weak fluorescence.

The reactivity of RO 2 . peroxide radicals in oxidation reactions depends greatly on specific and nonspecific solvation by the solvent. With increasing dielectric constant (ɛ) of the medium, the rate constant for the interaction of RO 2 . radicals with methyl ethyl ketone (k2) and the rate constant of the recombination of RO 2 . radicals (k6) increase. The specific solvation of RO 2 . radicals due to hydrogen bonds of water diminishes their reactivity. Equilibrium constants for the solvation of peroxide radicals and all rate constants of chain propagation and termination reactions involving solvated and unsolvated RO 2 . radicals were measured. The change in composition of the oxidation products when methyl ethyl ketone was diluted with benzene or water is caused by nonspecific and specific solvation by the solvent affecting the chain propagation reaction.

Ion association of onium centers with aromatic counterions is a useful alternative of the complexation of electron pairs with lanthanides for obtaining substantial signal displacements. With B(C6H5)4⊖, upfield shifts of up to 3 ppm are obtained. The effect is ascribed to the aromatic ring current; its peculiarities, compared with ordinary anion effects, are discussed.

Electronegativity difference is redefined as a scaling parameter, generalizing the concept of valence difference. A procedure for its evaluation is developed in terms of the dielectric constants of diatomic crystals. A simple alternative to the Clausius-Mossotti theory of the electronic dielectric constant is developed in terms of this concept. The effect of $d$-electron states and of hydrostatic pressure are discussed, and procedures for their approximate evaluation are developed. The treatment is extended to 68 crystals of the diamond, zincblende, wurtzite, and rock-salt types; values of the electronegativity parameter are tabulated for these crystals.

The β coefficients in the equation T1−1—T10−1=Σβscs, which represents the nuclear relaxation rate of 23Na+ in dilute aqueous solutions at 25° as a function of solute molarity, have been determined for a variety of ionic solutes and separated into cationic and anionic contributions. For many species β is simply expressed in terms of viscosity and volume effects. Large additional contributions to β are found for a group of symmetrical, singly charged oxy and fluoro anions of which ClO4=, studied in the previous paper, is typical. The same is true for ions such as SO4= and PO4−3 for which extra interaction (such as association) with Na+ has been deduced from other types of measurements. For some solutes, including sucrose, nonlinear contributions to T1−1 dominate at concentrations as low as 0.2M. In the case of SO4= the observed nonlinearity may be attributed to ion association, in which case a dissociation constant (molar scale) of 0.2, in agreement with the result of Davies may be deduced from the data if ...

The preparation of compounds with the general formula Ln(ClO4)3.4DB (where Ln = La-Yb, Y; DB = di-n-butyramide) is reported. The i.r. spectra support a trans-trans planar structure of the DB in the above compounds. The conductivity data of these complexes which vary between 161–170 ohm−1.cm2.mol−1 are probably far lower as a consequence of ion association. Absorption spectra in acetone, methanol and n-propanol are presented.

The variation with concentration of the dielectric constant of aqueous ionic solutions at low frequencies is explained in terms of the radial ordering of solvent molecules about the ions, and by the effects of temporarily linked ion pairs.

The remarkable achievements of Debye and Hückel, Onsager, and their colleagues in explaining and rationalizing the experimental data upon the behaviour of strong electrolytes in dilute solution have naturally led to much intensive research directed towards the extension of their theories to ranges of greater ionic concentration. From this work the theory of ion association, sponsored by Niels Bjerrum, has emerged with marked success. Assuming that the forces between oppositely charged ions obey the simple Coulomb law, Bjerrum has calculated the probability of such ions being within a distance, q 0 , at which the thermal energy per degree of freedom is but one-quarter of the electrostatic energy holding the ions together. Oppositely charged ions at less than this distance from one another are termed short-range pairs. The true degree of association (1— α *) of an electrolyte, as distinguished from the classical conception of undissociated molecules, is a measure of the number of short-range pairs, and Bjerrum has shown that the law of mass action may be applied to this association to develop a relation which reproduces the activities of electrolytes in more concentrated solution with remarkable fidelity. Onsager (1927) has calculated some approximate values of the true degree of association by consideration of the discrepancies between experimental conductivity data for aqueous solutions and the figures derived from his equation. Similar, and more extensive and more accurate measurements have been made by Davies (1927). In solvents of lower dielectric constant, the increased inter-ionic forces lead to still wider discrepancies, and many workers have shown that electrolytes which are almost completely non-associated in water are appreciably associated in solvents of reduced dielectric capacity. Martin (1928) has shown that the alkali metal halides are incompletely dissociated in benzonitrile and that the association obeys a generalized law of mass action. Fuoss and Kraus (1933 a ) have observed the same effects with the alkali metal nitrates dissolved in ammonia and other solvents of low dielectric constant. The mass-action constants derived from their results are in complete agreement with those predicted by the Bjerrum ion-association theory and, using measurements of the conductivity of tetra iso - amylammonium nitrate in dioxan-water mixtures, the same workers (1933 b ) have succeeded in extending the theory to include higher forms of association. Swift (1938) has confirmed the views of Fuoss and Kraus for ions of small radii by an investigation of the conductivities of solutions of the alkali metal halides in dimethylamine.

Studies of ion association reactions involving cadmium bromide and cadmium chloride have been made using cation exchange equilibrium measurements over the temperature range 0–98°. The cadmium chloride ion pair formation constants increase with temperature over the entire temperature range while those of cadmium bromide initially decrease and then increase at temperatures above about 60°. This results in a change in sign of the value of ΔH ° for the bromide ion association constant as the temperature is increased. Values of both the formation constants and enthalpies of formation for those ions agree with those found in the literature at 25°.

The molar activity coefficients of uni‐univalent electrolytes may be predicted on the basis of conductivity data with an accuracy of at least 1 percent up to concentrations of the order of 0.01 M in solvents of dielectric constant as low as 10. The method is based on Bjerrum's theory of ion association,1 with the ion pair dissociation constant evaluated from conductivity data.4–6 The success of the method depends on the use of expressions for y′, the quasi‐activity coefficient of the dissociated fraction, and for Λ, the equivalent conductivity, which go beyond the limiting law approximations of the interionic attraction theory. Equations (6), (8), (10), (12), and (13) have been developed for this purpose. In solvents of dielectric constant 10–40 the prediction involves no adjustable parameters characteristic of the electrolyte. The equations have been tested by comparing the conductivity‐predictedy values for hydrochloric acid with those determined from emf measurements. To insure the significance of this comparison, new emf data for the cell Pt–H2(g)/HCl AgCl–Ag have been obtained for 82.00 wt percent dioxane (D=10.56) in the concentration range 0.0001–0.01 M.

The complex cation Fe(Phen) 3 2+ [Phen = 1:10-phenanthroline] reacts with certain anions forming slightly dissociated usually insoluble compounds, extractable by organic solvents, in particular chloroform and nitrobenzene. The iodide complex Fe(Phen) 3 I 2 (“ferroin iodide”) has proved very suitable for the extraction and colorimetric determination of bivalent iron. High selectivity of the method is ensured by the addition of edta ∗ which masks all the elements which require consideration in practice.

The treatment of universal interactions is criticized and instead, the life-time of the complex is considered as a measure of the appearance of the com The splitting of solvent vibrational bands in the electrolyte solutions in water, acetonitrile and acetone is discussed and the quantum-chemical semi-e

The total measured concentration of an ionizable constituent of body fluids often fails to reveal either the varied chemical forms in which it may be present, or the portion which is present as the free ionized substance. This truism applies to most organic acids and bases and to inorganic ions which are multivalent. Univalent ions whose cor

The current-potential curves of some substitution-inert complex ions are affected by the change in the composition of the supporting electrolyte. The change in the one-electron reduction wave of hexaquochromium(III) ions with the increase in the concentration of sodium perchlorate and sodium iodide is analyzed in terms of the effect of the structure of the electrical double layer. The addition of sodium sulfate at a constant ionic strength of 0.1 shifts the half-wave potentials of hexaquochromium(III), hexamminechromium(III) and hexamminecobalt(III) ions to more negative potentials. In the case of hexamminecobalt(III), the shift is much greater than in the cases of the former two complex ions. These phenomena are interpreted to be due to the effects of the double layer structure and of the ion association.

The thermodynamic solubility products of CaSO4 and the free energies, enthalpies and entropies of the solution process have been obtained from know solubility data between 0 and 200 °C by calculating the activity coefficients of CaSO4 at high temperatures by means of the Bjerrum treatment of ion association. The thermodynamic solubility product of the n-hydrate is then given by K°sp=m2sγ2±anw and the thermodynamic functions are derived from this and tabulated.

The role of certain inorganic salts in increasing the flux of water through semipermeable membranes of cellulose acetate is related to the capacity of the component ions to swell the cellulosic substrate. The mechanism whereby ions which are high on the Hofmeister lyotropic series swell and dissolve secondary cellulose acetate has been investigated. Swelling is effected by the formation of metastable complexes involving the highly hydrated cationic fraction of the salt and both the hydroxyl and acetate groups of the cellulose acetate. Whereas effective anions possess large ionic radii and cause a breakdown in the structure of water which results in increased hydration of the cation, ineffective anions possess higher charge densities and tend to pair with the cation and decrease the latter's electrophilicity and hence hydratability. Ionic charge density is the factor of prime importance both with respect to the hydratability of the cation and the tendencies toward water disaggregation and ion association of the anion. The mechanism involved in the swelling of secondary cellulose acetate is related to swelling phenomena in many other polymers containing polar groups.

Difficulties encountered in estimating the solubility product constants of CaSO4 · 2H2O and CaCO3 from analytical measurements are discussed. A major factor involved is the formation of complexes between the constituent of the dissolving solid and other ionic species in solution. Conversely, when the solubility product principle using these constants is applied for predicting the precipitation of ions or the dissolution of a solid in fairly dilute solutions containing various ionic constituents, adequate accounting of all possible combinations of ion association must be made. Prediction problems are still present for solutions at high salt concentrations.