Electrolyte colloidal

Some electrolytes containing large ions, particularly soaps, dyes and many synthetic detergents, behave as normal electrolytes only in very dilute solution. At higher concentrations they show unusually low osmotic pressures and their conductances show large deviations from the Onsager relationship. 

After the critical concentration the conductance of the anion is observed to drop very sharply to zero and to pass into negative values. This is the same type of transport number behaviour as that shown by cadmium iodide (Chapter 2) and indicates that the anions are preferentially transported to the cathode rather than to the anode. It is evident that ion association between anions and positively charged micelles is the cause. Hartley calculated that in cetylpyridinium bromide about 53 bromide ions are associated with each micelle of 68 cationic species to give a net charge of +15. 

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The surface-active agents (surfactants) responsible for wetting, flotation and detergency exhibit rather special and interesting properties characteristic of what are called association colloids or, in the older literature, colloidal electrolytes. These properties play an important role in determining, at least indirectly, the detergency of a given surfactant and are therefore considered here... 

Fig. XIII-10. Properties of colloidal electrolyte solutions—sodium dodecyl sulfate. (From Ref. 102a.)...

Stigter, D, Kinetic Charge of Colloidal Electrolytes from Conductance and Electrophoresis. Detergent Micelles, Poly(methacrylates), and DNA in Univalent Salt Solutions, Journal of Physical Chemistry 83, 1670, 1979. 

Stearns, R.S., Oppenheimer, H., Simon, E., Harkins, W.D. (1947) Solubilization by solutions of long chain colloidal electrolytes. J. Chem. Phys. 15, 496-507. 

If the concentration of the diffusible electrolyte is small, relative to that of the colloid electrolyte, only a small quantity of salt will diffuse across the membrane, whilst if the electrolyte is present in relatively large quantities, there will obtain practically an equal distribution on either side of the membrane. A similar treatment permits of the calculation of the equilibrium distribution of a salt containing no ion in common with that of the colloid electrolyte. 

If pure water be placed in one compartment and the colloid electrolyte in the other, the diffusible ion will penetrate with an accompanying hydroxyl ion resulting in the formation of acid in one compartment, and alkali in the other. 

The value of Kw at ordinary temperatures is ca. 10 the percentage hydrolysis 100 - of the colloidal electrolyte can thus be... 

Figure 3.1a shows a membrane that is permeable to water and K+ and Cl - ions but impermeable to colloidal electrolytes (polyelectrolytes such as charged proteins). Let a denote the interior of the cell and (3 the extracellular region. In the absence of the poly electrolyte, water, K + and Cl" partition themselves into the two sides such that the chemical potentials of each species are the same inside as well as outside, as thermodynamics would demand. Moreover, the requirement of electroneutrality in both ot and (3 demands that the concentrations of each species K + and CP be the same on either side of the partition. 

Some Properties of Interfacial Films of Colloidal Electrolyte-Protein Complexes... 

A 0.01 mol dm-3 aqueous solution of a colloidal electrolyte (which can be represented as Na15X) is on one side of a dialysis membrane, while on the other side of the membrane is an equal volume of 0.05 mol dm-3 aqueous sodium chloride. When Donnan equilibrium is established, what net fraction of the NaCl will have diffused into the compartment containing the colloidal electrolyte ... 

A kind of colloidal electrolyte consisting of a macromolecule that, when dissolved, dissociates to yield a polyionic parent macromolecule and its corresponding counterions. Also termed polyion , polycation , or polyanion . Similarly, a polyelectrolyte can be referred to in certain circumstances as a polyacid , polybase , polysalt , or polyampholyte (Ref. [978]). Example carboxymethylcel-lulose. 

Solutions of soaps and other long-chain Colloidal electrolytes. The surface tension of soaps has been very extensively studied,1 but for the most part the results in the literature are discordant far beyond the usual error of measurement of surface tension. In general the surface tension diminishes rapidly with increasing concentration, reaching a steady, or nearly steady, low value after a certain concentration is reached this concentration is naturally lower the longer the hydrocarbon chain. The variation between the results obtained by different experimenters, and even by the same experimenter under different conditions, may... 

Stability of isolated liquid films soap films foams. Pure liquids rarely, if ever, foam, but most solutions of capillary active substances do so to a greater or less extent, and long-chain colloidal electrolytes, particularly the soaps, have an almost miraculous power of rendering liquid films stable. Dewar1 has maintained soap films unbroken for over a year (one for three years ), with due precautions against evaporation, mechanical and thermal shocks, and absorption of carbon dioxide. 

Very great precautions must be taken against accidental contamination of the surface, which cannot be renewed except by removing the bubble or drop, and replacing it by a new one. The method has recently proved useful with metals, and in studying the slow changes of surface tension which take place in solutions of some colloidal electrolytes. 

Solutions of soaps and other long-chain colloidal electrolytes... 

The n-butylammonium vermiculite system is an example of a three-component system of a monodisperse colloid, electrolyte and solvent. There are four constituents in the macroionic solution — the negatively charged clay plates, n-butylammonium ions (counterions), chloride ions (co-ions), and water — but these may not vary independently because they are subject to the restriction that... 

Chemical equilibrium in heterogeneous systems (from the thermodynamic standpoint) when capillary or electrical effects are of importance—Adsorption—Donnan s theory of membrane equilibria—Micelle theory of colloidal electrolytes... 

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