Electrolyte solutions in water

Verell, R. E. Infrared Spectroscopy of Aqueous Electrolyte Solutions, in Water — a Comprehensive Treatise (ed. Franks, F.), Vol. 3, chapter 5, New York, Plenum Press 1973... 

Although activity is regarded as 1 in dilute solutions this is still an approximation. The activity of an electrolyte solution in water can be estimated from the following equation ... 

In the present chapter, the properties of electrolyte solutions in water are discussed in detail. Initially the solvation of ions in infinitely dilute solutions is considered on the basis of the Born theory. Then, the Debye-Hiickel model for... 

Inclusion of the change in solvent permittivity in the MSA description is an effective way of dealing with the change of solvent properties which accompany the addition of an electrolyte to a polar solvent. Since permittivity data are now available for a large number of electrolyte solutions in water [23], the MSA model can be applied to a wide variety of systems. However, there is one feature of electrolyte solutions which has been neglected in the treatments presented up to this point, namely, the existence of ion aggregates. This feature of electrolyte solutions is discussed in the following sections of this chapter. 

The change in surface potential at the air interface has been studied for a variety of electrolyte solutions in water [6, 10]. The results are reported as A% where... 

Sources for hydrogen include 1) electrolysis of a suitable electrolyte solution in water, 2) reaction of steam with a metal, 3) reaction of water with a nonmetal, and 4) synthesis gas or water gas. From the Ellingham diagram, the water-gas shift reaction is feasible below about 1100 K,... 

For mixed electrolyte solutions in water, the experimental excess free energy functions have been given in parameterized form by Pitzer, and excess free energies and enthalpies have been tabulated by Anderson and Wood. "" ... 

The distribution of the ions in the solution from the interface can be readily obtained from the Boltzmann law (Equation 3.12) by using the result for the potential. The distributions of counterions and coions are given in Figure 3.11b for 0.1 and 1M monovalent electrolyte solutions in water at T = 25 C, by keeping the surface charge density at the constant value of 1 per nm. For each electrolyte concentration, the upper curve represents the counterion... 

In Chapter 6 we saw that the chemistry of sodium can be understood in terms of the special stability of the inert gas electron population of neon. An electron can be pulled away from a sodium atom relatively easily to form a sodium ion, Na+. Chlorine, on the other hand, readily accepts an electron to form chloride ion, Cl-, achieving the inert gas population of argon. When sodium and chlorine react, the product, sodium chloride, is an ionic solid, made up of Na+ ions and Cl- ions packed in a regular lattice. Sodium chloride dissolves in water to give Na+(aq) and C (aq) ions. Sodium chloride is an electrolyte it forms a conducting solution in water. 

For interfaces between liquid electrolytes, we can distinguish three cases (1) interfaces between similar electrolytes, (2) interfaces between dissimilar but miscible electrolytes, and (3) interfaces between immiscible electrolytes. In the first case the two electrolytes have the same solvent (medium), but they differ in the nature and/or concentration of solutes. In the second case the interface separates dissimilar media (e.g., solutions in water and ethanol). An example for the third case is a system consisting of salt solutions in water and nitrobenzene. The interface between immiscible dissimilar liquid electrolytes is discussed in more detail in Chapter 32. 

Viscosity of copolymer solutions decreases by, at most, 3 percent when electrolyte concentration changes from 0 to 0.342 M sodium chloride or 2.45 x 10 M calcium chloride. Viscosity of hydrolyzed polymer solutions decreases exponentially with increasing electrolyte concentration in water. 

Electroosmosis or electroendosmosis is the bulk movement of the solvent (electrolyte solution) in the capillary caused by the zeta (0 potential at the wall/water interface of the capillary. Any solid-liquid interface is surrounded by solvent and solute constituents that are oriented differently compared to the bulk solution. Figure 17.2 illustrates a model of the wall-solution interface of the widely applied capillaries. Owing to the nature of the surface functional groups, in silica capillaries the silanol groups, the solid surface has an excess of negative... 

The activity of the solvent (water) in a solution of pure electrolyte dissolved in water can be computed by application of the Gibbs-Duhem equation ... 

Bennion, D. N. Mass Transport of Binary Electrolyte Solutions in Mewbranes, Water Resources Center Desalination Report No. 4 Department of Engineering, University of California—Los Angeles 1966. 

Millero F. J. (1972). The partial molal volumes of electrolytes in aqueous solutions. In Water and Aqueous Solutions, R. A. Home (series ed.), New York Wiley Interscience. 

For the purposes of discussion, we distinguish between two types of electric conductance metallic and electrolytic, the first being a stream of electrons, as in a copper wire, the second being a stream of ions, as in the case of a salt solution in water. In this case, positive ions will drift in the direction of the cathode, whereas negative ions will drift in the direction of the anode. 

Because Na(Hg) slowly reacts with water, the Na(Hg) electrode in cell (1) is preferably a flow type, in which the electrode surface is continuously renewed. Ethylamine is used in cell (2) because it does not react with Na and Na(Hg) but dissolves and dissociates electrolyte Nal. The composition of the electrolyte solution in cell (2) does not influence its emf. Instead of measuring the emfs of cells (1) and (2), we can measure the emf (-3.113 V) of the double cell (4). The advantage of the double cell is that the emf is not influenced by the concentration of Na(Hg) ... 

For example, 100 ml of air at 25 °C and at 100% humidity contains about 2.5 mg of water. Therefore, when we handle electrolyte solutions in non-aqueous solvents, we must estimate the amount of water introduced from the air and the extent of its effect on the measurements. The vacuum line techniques and the glove box operations for electrochemical studies in non-aqueous solvents have been dealt with in several books. See, for example, Kissinger, P.T., Heineman, W. R. (Eds) Laboratory Techniques in Electroanalytical Chemistry, 2nd edn, Marcel Dekker, New York, 1996, Chapters 18 and 19. 

When chemists began to use electricity as one of their tools, they discovered that, different solutions behaved in different ways. The solution in water of a great number of chemicals — sugar among them — did not let electricity pass through. They were non-conductors. Some chemicals, on the other hand, conducted electricity very easily. They were good conductors — electrolytes. ... 

Figure 18.13 Vacuum electrochemical cell with an integrated drying tube (o) and water-cooled jackets (fl, fZ) from (A) a front view and (B) a top view. Schematic representation of the drying operation is shown in A, B and C. The cell is filled with aluminum oxide and electrolyte solution in A. The solution is transferred into the cell by a 90° rotation in B. After back-rotation, the solution flows into the electrode compartment, passing through the cooled alumina drying tube in C. [From Ref. 2, with permission.]...

The standard state is defined as the hypothetical state that would exist if the solutewere at a concentration oTTMTbut with the molecules experiencing the environment of an extremely dilute solution with this standard state, activity coefficients approach unity with increasing dilution. For electrolytes in dilute solution in water, the departure of the coefficients from unity can be calculated from the Debye-Hiickel relationship.8... 

Mercury represents a serious environmental risk, and the study of removal of mercury from wastewater has received considerable attention in recent years. Mercury concentration was usually reduced by deposition on a cathode with high surface area. Removal of mercury is studied using extended surface electrolysis which reduces the level of mercury to below acceptable concentrations of 0.01 ppm in wastes by employing a Swiss roll cell with a cadmium-coated, stainless-steel cathode. An industrial cell with a fluidized bed electrode has also been studied. Graphite, as an efficient porous electrode, has been used to remove traces of mercuric ions form aqueous electrolyte solutions. In order to apply the electrochemical method for some effluents, it is necessary to use sodium hypochlorite to convert elemental mercury and less soluble mercury compounds to water-soluble mercuric-chloride complex ions. 

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