Ions Of Opposite Charge Research Articles

Application of irreversible thermodynamics to isotopic diffusion. Part 1.—Isotope–isotope coupling coefficients for ions and water in concentrated aqueous solutions of alkali metal chlorides at 298.16 K

From literature sources irreversible thermodynamic parameters may be obtained for all alkali metal chloride salt solutions at 298.16 K in the concentration range 0–3.0 mol dm–3. Comparable data for isotopic diffusion coefficients of component ions and water are incomplete. These have been obtained in this study, using a diaphragm cell, for all but rubidium ion in rubidium chloride. It is shown that these two sets of data may be combined to yield Onsager frictional coefficients (rii*) or mobility coefficients (lii*) which measure the kinetic interaction between isotopes as a function of concentration for each salt solution. Interpretation of lii* for ions is made difficult because of large frame-of-reference contributions with water solvent, but these may be compared with values calculated from the Onsager limiting law. Frictional interpretations are more explicit. The main factor contributing to the experimental diffusion coefficient for ions, Dii, remains ion-water friction which amounts to some 90 % for many slats even at 3.0 mol dm–3. The primary cause is that interionic friction between ions of opposite charge is largely cancelled by isotope–isotope friction in the expression for Dii.

Heats of dilution of sub-micellar aqueous surfactant solutions

Heats of dilution of sub-micellar solutions of a series of sodium alkyl sulphates and alkyl-trimethylammonium bromides are reported and two possible interpretations of the observed deviations from simple Debye-Huckel theory are given. The first is in terms of dimerisation of the surfactant ions. The second is that the effective distance of closest approach of ions of opposite charge decreases with increasing temperature because of corresponding decreases in hydrophobic hydration of the alkyl chains of the surfactant ions. Neither interpretation is to be preferred to the other on the basis of evidence currently available.

Some Applications of Time-Dependent Rate Constant Theory to Radiation Chemistry

It is well known that rate constants for diffusion-limited reactions decrease with time after the start of an experiment, an effect due to the time required to establish a diffusion gradient of each reactant around the other. It is pointed out that slow reactions between ions also exhibit a time dependence because a finite time is required to establish the Boltzmann distribution of each type of ion around the other. The latter effect appears as an increase of rate constant with time for reactions between ions of opposite charge and a decrease for ions of similar charge. These time dependent effects are applied to the picosecond pulse radiolysis results of Wolff et al. on electron formation and decay in acetone and acid solutions, and to some competition experiments of Czapski and Peled. Effects attributed by them to reactions of a precursor of the hydrated electron are shown to be similar to expected consequences of time-dependent phenomena of the hydrated electron itself.

Electrostatic charge generation during nonuniform flow of hydrocarbons through porous insulators

Abstract The generation of charges in liquid hydrocarbons passing through a thin porous disc of electrically insulating materials sandwiched between two perforated metal discs (electrodes), all located within a nonmetallic pipe, was investigated by measurement of the electric current between the electrodes. The current transients observed after flow initiation were—except for the time scale—analogous to those sometimes found during the charging of condensers containing dielectrics; presumably the penetration of ions of opposite charge is unequally resisted by the disc containing an initial concentration of surface charges, thus giving rise to temporary charge accumulations. Particularly large transients were found to follow rapid changes of fluid composition. The results have implications on the percolation of liquid insulators through beds of clay and similar materials.

Mössbauer spectra of 57Fe in ion exchange resins

Mössbauer spectra have been recorded for different cation exchange resins containing Fe 2+ and Fe 3+ ions. The resins studied are both of the polystyrene sulfonic acid type with varying degrees of crosslinking and of the polyphenol sulfonic acid type. Great care was taken in the preparation of the resins to avoid the formation of iron chloride and hydroxide complexes. The width of the absorption lines was found to be more than three times larger than the width generally observed in crystalline substances. From a discussion of different line-broadening mechanisms it is concluded that the broadening is probably caused by variations in the value of the electric field gradient tensor in the different cationic sites in the noncrystalline lattice. In the case of Fe 3+ ions simulataneous variations in the chemical shift may also contribute to the line broadening. Absorption of water in the resins containine Fe 2+ ions was accompanied by a decrease of the intensity of the Mössbauer absorption. This was interpreted as a “solvation” effect weakening the bond between the ions of opposite charge. The experimental results indicate that at water contents < 6 H 2O per anionic group, the water is mainly adsorbed at the ionic groups in the polystyrene type resins, while in the polyphenolic resin water adsorption probably also occurs at the oxygen bridges in the polymer.

Preparation of the Skin For Lumbar Puncture

To the Editor:— We would like to call attention to Skin Preparation for Lumbar Puncture: Ether or Soap? (208:1196, 1969). Dr. Harvey Bernard, MD, of the Albany Medical College replied to the question concerning the use ofhexachlorophene(Septisol) followed by benzalkonium chloride for skin preparation before lumbar puncture. We would like to submit the following additional information concerning the skin cleansing procedure. Benzalkonium (Zephiran) chloride, along with benzathonium ( Phemerol) chloride, and cetylpyridium ( Ceepryn) chloride are quanternary ammonium cationic surface-acting agents and germicides. When these germicides come in contact with anionic soaps, as are found in hexachlorophene ( Septisol and Phisohex), the large organic ions of opposite charges are attracted to one another, and decrease or destroy the bacteriostatic activity of the cationic surface-acting germicides.1,2 When surfaces have been washed with soap they must be thoroughly rinsed with water to remove any residual soap before applying a quanternary ammonium

The Interaction Energy of an Ion Pair with Overlapping Hydration Shells. II. A Spheroidal Cavity Model

The energy of interaction of two monovalent ions of opposite charge with overlapping hydration shells and in an aqueous medium is discussed in terms of a spheroidal cavity model. Some of the calculations carried out in an earlier paper by Levine and Rosenthal (1966) are shown to be inadequate and an improved model is tested for consistency with the "truncated spheres model" proposed in Part 1. The calculations suggest that this new model can be adapted to an examination of the water molecules in the first hydration shells of an ion pair. Only calculations for the K + and F- ions are included.

The Interaction Energy of an Ion Pair with Overlapping Hydration Shells. I. A Truncated Spheres Model

The energy of interaction of two univalent ions of opposite charge with overlapping hydration shells and in an aqueous medium is discussed in terms of a truncated spherical cavity model. The general trend of the effective dielectric constant considered as a function of the separation between the ion centres is found to be in agreement with some earlier results on a spheroidal cavity model. The present investigation has the advantage that the boundary of the ion pair , varies continuously with separation and hence that no matching of a two� sphere model onto a spherical cavity model is required. It is found that the effective dielectric constant has a maxinum value at very small ion overlap.

Enthalpy of hydration of the proton

A method is presented for estimating the absolute hydration enthalpy of the proton at infinite dilution and at 298 c- K. The method makes use of a simple model of aqueous solutions, and is based on the significance of differences between thermodynamic hydration functions for ions of opposite charge. Values of the differences between conventional hydration enthalpies are plotted against (R + alpha )/sup -3/, where R is the effective radius of the ion and alpha is the effective radius of the water molecule. This plot yields the absolute hydration enthalpy of the proton. The value obtained is -260.7 kcal mole/sup -1/ with an estimated uncertainty of surface proces 2.5 kcal mole/sup - 1/. An estimate of the quadrupole moment of the water molecule is also made. (auth)

Electron Paramagnetic Relaxation in Ionic Solutions

The interaction of paramagnetic cations with paramagnetic anions in solution is considered. The resultant broadening of the paramagnetic resonance lines of one of the species can be used to measure rates of formation of ion-pairs in cases in which the interaction is strong. Experimental results are given for a number of ions in water and compared to theoretical rates of diffusion controlled reactions between ions of opposite charge. The effect of the presence of inert, diamagnetic ions in the solution is considered.

Some membrane properties of the effector in the galvanic skin response.

Several membrane-like properties of the effector in the galvanic skin response (GSR) have been measured in humans by comparison of activity at a control site with that of a site subjected to changes of external chemical environment or changes in direction or density of imposed current. Comparison of inorganic chlorides shows that small cations, e.g. K+, may reversibly reduce GSR amplitude and R by 40%; larger cations, e.g. Ca++, increase GSR by several hundred per cent, while at the same time reducing basal resistance (R). GSR and R are reduced by acids and alkalies and by detergents. The effector is a poor rectifier, but there is a pronounced effect of polarity of current on the amplitude of the GSR in the case of large cations or anions combined with smaller ions of opposite charge. Current densities beyond 11 μamp/cm2 produce an ‘injury’ effect manifested in GSR and apparent resistance. These results have been interpreted in terms of an active superficial membrane having a relatively low charge. Submitted on August 3, 1959

Effects of Double Exchange in Magnetic Crystals

This paper discusses some effects of mobile electrons in some lattices. It is shown that these electrons (or holes) always give rise to a distortion of the ground state spin arrangement, since electron transfer lowers the energy by a term of first order in the distortion angles. In the most typical cases this results in: (a) a nonzero spontaneous moment in low fields; (b) a lack of saturation in high fields; (c) simultaneous occurrence of and antiferromagnetic lines in neutron diffraction patterns; (d) both ferromagnetic and branches in the spin wave spectra. Some of these properties have indeed been observed in compounds of mixed valency such as the manganites with low ${\mathrm{Mn}}^{4+}$ content. Similar considerations apply at finite temperatures, at least for the (most widespread) case where only the bottom of the carrier band is occupied at all temperatures of interest. The free energy is computed by a variational procedure, using simple carrier wave functions and an extension of the molecular field approximation. It is found that the canted arrangements are stable up to a well-defined temperature ${T}_{1}$. Above ${T}_{1}$ the system is either or ferromagnetic, depending upon the relative amount of mobile electrons. This behavior is not qualitatively modified when the carriers which are responsible for double exchange fall into bound states around impurity ions of opposite charge. Such bound states, however, will give rise to local inhomogeneities in the spin distortion, and to diffuse magnetic peaks in the neutron diffraction pattern. The possibility of observing these peaks and of eliminating the spurious spin-wave scattering is discussed in an Appendix.

Water and ion flow across cellulosic membranes

AbstractThe primary objective of this investigation has been to explain why cellulose acetate behaves as a semipermeable membrane in saline water. To explain this phenomenon, two different mechanisms for the transfer to water and ions through cellulose acetate membranes were formulated. Those ions and molecules that cannot enter into hydrogen bonding with the membrane are transferred by hole‐type diffusion. The rate of diffusion appears to be governed by a water‐cellulose acetate structure. The reaction between water and the cellulose polymers to form bound water regions is favored by compressing the membrane. As pressure is applied on the membrane, more bound water is produced, which causes the rate of hole‐type diffusion to decrease. On the other hand, those ions and molecules that can associate with the membrane and are transported through it by alignment‐type diffusion. The formation of the water‐cellulose acetate structure does not appreciably diminish the diffusion rate of water through the membrane. Cellulose acetate begins to behave as an effective semipermeable membrane in saline water when it is compressed sufficiently to retard greatly the diffusion of NaCl. Several types of experiments were conducted to support these hypotheses. The most important evidence was obtained from resistance experiments. The electrical resistances of specific ions was measured across cellulose acetate at various pressures by using permselective membranes to prevent migration of the ion of opposite charge. It was observed that the rate of diffusion of those ions that cannot combine with the membrane actually does decrease as the membrane is compressed. The rate of diffusion of H3O+, which can enter into hydrogen bonding with cellulose acetate, is much higher and is not appreciably reduced as the membrane is compressed. These resistance‐pressure relationships are correlated with the semipermeability of the cellulose acetate.

Effect of field intensity and quantity of electricity upon counterion fixation by polyelectrolytes

AbstractNumerous transference experiments on polyelectrolytes have demonstrated that an appreciable fraction of the counterions move during electrolysis with the polyelectrolyte ion of opposite charge. The present studies were carried out to determine the effect of field intensity and the extent of electrolysis on the apparent degree of counterion fixation. It is found that the degree of ion binding depends upon the applied field and that up to a certain point the association diminishes with increasing field. The results are interpreted to mean that the ions are not all held equally firmly. Some ions are held loosely and move as a kind of atmosphere with the polymer ions only when the applied field is small. Other ions are firmly held and are carried along even in the presence of a strong field which would tend to cause separation of the oppositely charged ions. Using polyacrylic acid partially neutralized with sodium hydroxide, it is observed that from 10 to 20% of the ions that are bound are “loosely” bound and hence not carried along under strong fields. As might be expected, the different degrees of binding are observed to be functions of the degree of neutralization.

Theory of Ion Exchange for Polyelectrolytes Undergoing Electrolytic Transference

It has been observed experimentally that polymeric ions generally have associated with them a large number of small ions of opposite charge. These smaller ions, which are considered bound to the polymeric ions, are capable of exchanging with free ions in solution. The rate of this exchange can be determined by certain electrolytic transference experiments involving the use of radioactive tracers. The theory of such transference experiments is worked out by formulating and solving appropriate differential equations subject to certain boundary conditions. It is then shown how results of these transference studies can be used for evaluating ion rate exchange constants.

Calculation of Surface Areas from Measurements of Negative Adsorption

WHERE a charged surface is in contact with a solution of electrolyte, the ions of opposite charge are attracted to the surface while those of like charge are repelled from it. I considered that it would be possible to compute the negative adsorption of the repelled ions from the basic assumptions of Gouy's theory of the diffuse electric double layer, and therefore invited Mr. M. H. Quenouille to tackle the mathematical difficulties involved. Complete solutions have now been obtained for electrolytes in which the ions have valency ratios 1:2, 1:1, and 2:1, and a full account of this work will be submitted for publication shortly.

Flocculation and peptization in oil as dispersion medium

AbstractExperiments on the flocculation of suspensions in a mineral oil show that high viscosity gives rise not only to low flocculation velocity but also to very slight adhesion of the particles. In a mineral oil as a viscous non‐aqueous liquid the influence of viscosity and temperature on the kinetics of colloidal phenomena can be investigated over a much wider range than in water.The effect of peptizers is investigated and a case is described in which two peptizers counteract each other. This is remarkable in view of the fact that the current explanation involving ions of opposite charge cannot be given.

The Effect of Electrostatic Forces on Electrokinetic Potentials

Assuming that the ions in solution near a charged wall are subjected only to electrostatic and kinetic forces, it is shown that the potential gradient normal to the wall is determined principally by the valence and concentration of the ion of opposite charge to the wall. Assuming that the valence and concentration of this ion determine the effect of the salt on the electrokinetic potential of the wall, the surface potential of the wall and the thickness of the immobilized liquid layer are calculated from electrokinetic potential data. Salts of ``normal'' ions (NaCl, BaCl2, etc.) cause relatively small changes in the surface potential and thickness of the immobilized layer at a glass surface and these changes occur only at very low salt concentrations. Salts containing ``abnormal'' ions (H+, OH—, La+++, etc.) produce larger changes and the change continues over a much wider concentration range. The extreme effectiveness of salts like AlCl3 and ThCl4 in lowering negative electrokinetic potentials cannot be accounted for by the higher valence of the ions.

NUTRIENT DEFICIENCIES AND GROWTH HORMONE CONCENTRATION IN HELIANTHUS AND NICOTIANA

THE RELATION of mineral nutrients to the production of growth hormone in plants pertains directly to the problem of plant development. Shoot tips are the main centers of growth in higher plants; they are also the main centers of hormone production. The continuous initiation and subsequent expansion of new organs in such regions depends upon the successful mobilization of the raw materials needed for growth; likewise, the continued production of hormone depends upon the presence of the proper raw materials. Studies on the growth hormone content of Helianthus and Nicotiana (Avery, Burkholder, and Creighton, 1936) have shown (1) that the hormone is scarcely detectable in the absence of supplied nitrogen; (2) that, within certain limits, hormone concentration is in proportion to the amount of nitrate supplied to plants grown in sand culture; (3) that shoot tips of Nicotiana grown in field experimental fertilizer plots exhibit no relationship between miiieral deficiencies and hormone content. From the latter it was concluded that the degree of deficiency observable in field-grown material was not sufficient to decrease the content of growth promoting substances in shoot tips. Before further studies on this subject were undertaken, the necessity became clear for establishing the relationship between mineral nutrition and growth hormone production with plants grown under controlled conditions in sand cultures. INVESTIGATION.-Growth hormone concentration in relation to varied proportions of nutrient ions.-The relationship of growth hormone concentration to varied nutrient ion proportions was studied in Helianthus annunts L. grown in sand cultures. In this work, a nine-salt solution was employed so that it was possible to vary in any single series of solutions the concentration of any cation or anion over a wide range without extensively altering the relation of the concentrations of the ions of opposite charge to each other (Beckenbach, Wadleigh and Shive, 1936). A list of the salts employed and the amounts used for making up the different culture solutions may be found in table 1. The nine salts containing the essential elements-nitrogen, phosphorus, potassium, calcium, magnesium, sulphur-were used in amounts appropriate to yield nutrient solutions with five of the ions in arbitrary standard concentration for each series of solutions, and one selected ion was varied so as to give relative concentrations as follows: times the standard, 1 (standard), 0.1, 0.02, 0.01 times the standard, and none. For example, the 4 nitrogen culture solution contained times as much

The influence of the underlying surface on the cataphoretic mobility of adsorbed proteins

Our knowledge of the structure of the electrical double layer at the interface between a solid and a liquid is so indefinite that it is difficult to give a precise definition or to make an exact measurement of electrokinetic potential. In the liquid in the immediate vicinity of the solid surface, there will be an excess of ions of opposite charge to that on the surface, forming an electrical double layer which is approximately a molecular diameter in thickness. All the potential drop, however, is not confined to this first double layer ; the excess ions in the solution are not rigidly held to the surface, they are able to break away and to form a diffuse layer which extends some distance into the solution. Experience has shown that gentle stirring of the solution can influence the distribution of these ions, and it is probable that the diffuse layer extends as far as 10 -5 to 10 -4 cm. from the solid surface. It is this diffuse layer of more or less loosely held ions which is responsible for the electrokinetic properties of liquids in contact with solid surfaces. No exact relation has been established connecting the diffuse, or electrokinetic potential, with the total potential drop between a solid and a liquid. Usually they are of the same sign, but there is evidence that the potential drop across the diffuse layer can even be opposite in sign from the main potential, indicating a twofold double layer. The presence of polar molecules adsorbed at the interface may have a profound effect on the distribution of the diffuse layer without sensibly affecting the total potential difference. Further work on the relationship between these quantities would be valuable.