Electrolyte potential

Zirconium tetrachloride forms hexachlorozirconates with alkab-metal chlorides, eg, Li ZrCl [18346-96-8] Na2ZrClg [18346-98-0] K ZrCl [18346-99-1y, Rb2ZrClg [19381 -65-8] and Cs2ZrClg, and with alkaline-earth metal chlorides SrZrCh [21210-13-9] and BaZrCl [21210-12-8]. The vapor pressure of ZrCl over these melts as a function of the respective alkah chlorides and of ZrCl concentration were studied as potential electrolytes for the electrowinning of zirconium (72). The zirconium tetrachloride vapor pressure increased in the following sequence Cs < Rb < K < Na < Li. The stabiUty of a hexachlorohafnate is greater than that of a comparable hexachlorozirconate (171), and this has been proposed as a separation method (172). 

Unsaturated sulphone Reduction potential (Electrolyte) Product Coulometry (F mol-1) Ref. 

Aromatic unsaturated sulphones Reduction potentials (electrolyte)4 Main product Coulometry (FmoL1) Ref. 

Cobalt(II) complexes of three water-soluble porphyrins are catalysts for the controlled potential electrolytic reduction of H O to Hi in aqueous acid solution. The porphyrin complexes were either directly adsorbed on glassy carbon, or were deposited as films using a variety of methods. Reduction to [Co(Por) was followed by a nucleophilic reaction with water to give the hydride intermediate. Hydrogen production then occurs either by attack of H on Co(Por)H, or by a disproportionation reaction requiring two Co(Por)H units. Although the overall I easibility of this process was demonstrated, practical problems including the rate of electron transfer still need to be overcome. " " ... 

Some of the components of the EDL, such as a nonuniform electron distribution in the metal s surface layer and the layer of oriented dipolar solvent molecules in the solution surface layer adjacent to the electrode, depend on external parameters (potential, electrolyte concentration, etc.) to only a minor extent. Usually, the contribution of these layers is regarded as constant, and it is only in individual cases that we must take into account any change in these surface potentials, and which occurs as a result of changes in the experimental conditions. 

Cathode Cathode potential Electrolyte (V) Quantity of electricity (C) Current efficiency (%) Concentration of carboxylic acid ( x 10 3 mol/dm3) ... 

Proton, that is, H+ ion, conductors are of importance as potential electrolytes in fuel cells. There are a number of hydroxides, zeolites, and other hydrated materials that conduct hydrogen ions, but these are not usually stable at moderate temperatures, when water or hydroxyl tends to be lost, and so have only limited applicability. 

Condensation of p-acetylben-zenediazonium bromide with acrylic acid, 51, 1 Conduritol-D, 50, 27 Conjugate addition of Grignard reagents, 50, 41 CONTROLLED POTENTIAL ELECTROLYTIC REDUCTION 1,1-BIS (BROMOMETHYL)CYCLOPROPANE,... 

Earlier, Gavach et al. studied the superselectivity of Nafion 125 sulfonate membranes in contact with aqueous NaCl solutions using the methods of zero-current membrane potential, electrolyte desorption kinetics into pure water, co-ion and counterion selfdiffusion fluxes, co-ion fluxes under a constant current, and membrane electrical conductance. Superselectivity refers to a condition where anion transport is very small relative to cation transport. The exclusion of the anions in these systems is much greater than that as predicted by simple Donnan equilibrium theory that involves the equality of chemical potentials of cations and anions across the membrane—electrolyte interface as well as the principle of electroneutrality. The results showed the importance of membrane swelling there is a loss of superselectivity, in that there is a decrease in the counterion/co-ion mobility, with greater swelling. 

When the relative permittivity of the organic solvent or solvent mixture is e < 10, then ionic dissociation can generally be entirely neglected, and potential electrolytes behave as if they were nonelectrolytes. This is most clearly demonstrated experimentally by the negligible electrical conductivity of the solution, which is about as small as that of the pure organic solvent. The interactions between solute and solvent in such solutions have been discussed in section 2.3, and the concern here is with solute-solute interactions only. These take place mainly by dipole-dipole interactions, hydrogen bonding, or adduct formation. 

Another method of producing ions in solution is the dissolution of a potential electrolyte in water ... 

In the pure state, a potential electrolyte such as oxalic acid (HOOCCOOH) consists of uncharged molecules. A true electrolyte such as NaCl in the pure state consists of two separate ions, Na and CP. The proton is a bare nucleus it has no electrons. It is chemically unstable as an isolated entity because of its affinity for electrons. As a result, the proton reacts with the free electron pair of oxygen in the H2O molecule. 

CONTROLLED-POTENTIAL ELECTROLYTIC REDUCTION 1,1-BIS(BR0M0METHYL)CYCL0PR0PANE... 

Figure 1. Cell for eontrolled-potential electrolytic reduction.

In another study involving C78, a pure sample of the C2v isomer was prepared using the cyclopropanation-retro-cyclopropanation reaction sequence [44, 64]. This reaction scheme consists of a controlled potential electrolytic (CPE) reduction of a previously synthesized cyclopropane derivative of the isomer, leading to removal of the cyclopropane moiety (s), (see Sect. 6.1.5). A pure sample of the D3 isomer was obtained by high performance Kquid chromatography (HPLC) as previously described [49, 65]. The redox behavior of both isomers, in DCM at room temperature, reveals that their cathodic electrochemistry is indeed very similar (although not identical) in this solvent [44]. The first two reductions are easier for the D3 isomer by 60 and 100 mV, respectively, while the third and fourth reductions are nearly identical for the two... 

An alternate method for cyclizing ae./i-dihalobutanes is to use a controlled potential electrolytic reduction. 10 12 This method appears to be superior to the conventional reductive cyclization of 1,4-dihalobutanes with metals. Dibromides generally give better results than dichlorides in an aprotic solvent such as dimethylformamide or acetonitrile. Thus, a DC voltage of 1.8-3.0 V was applied for 6 hours to a solution of 1,4-dibromobutane (50 g) in dimethylformamide (1 L) in a cell consisting of a mercury cathode and a nichrome anode, to give cyclobutane and butane in 25 and 75 % yield, respectively.10,11 The experimental setup has been described in a detailed procedure.12... 

Throughout most of this chapter the emphasis has been on the evaluation of zeta potentials from electrokinetic measurements. This emphasis is entirely fitting in view of the important role played by the potential in the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. From a theoretical point of view, a fairly complete picture of the stability of dilute dispersions can be built up from a knowledge of potential, electrolyte content, Hamaker constants, and particle geometry, as we discuss in Chapter 13. From this perspective the fundamental importance of the f potential is evident. Below we present a brief list of some of the applications of electrokinetic measurements. 

Fig. 38. Irregular spatiotemporal behavior during H2 oxidation on a Pt ring at a fixed external potential. Electrolyte 0.5 mM H2SO4, 10 5 M Cu2+, 0.1 mM Cl-. (For clarity, the homogeneously oscillating part of the data has been subtracted.)...

As this example shows, the decisive factor for the dissociation of polar compounds (HC1, NH3) is first of all the formation of stable ions (H30+, NH+) the components of which are held together by chemical, covalent bonds. Because such compounds form ions only under the influence of a solvent, they are sometimes called potential electrolytes. 

Electrolytic conductance, a property of the so called conductors of the second class, is encountered mainly in the case of salts in dissolved, melted and solid state. Among these compounds are sulphates, halides, nitrates, silicates, also many oxides, hydroxides, sulphides and so on. The same group includes also the potential electrolytes, i. e. the substances from which ions are formed only in mutual reaction with a solvent (solutions of acids in basic solvents, solution of bases in acid solvents, further amines and different chlorine derivatives of organic compounds in liquid sulphur dioxide, nitro-compounds in liquid amines etc.). Finally also numerous colloidal solutions (such as proteins and soaps) conduct the current like electrolytes. 

Electrolyte — Compounds that dissociate (- dissociation) into -> ions upon dissolution in -> solvents or/and upon melting and which provide by this the - ionic conductivity. Also, compounds that possess in the solid state a rather high ionic conductivity are called - solid electrolytes. - True electrolytes are those which are build up of ions in the solid state (or pure form), whereas potential electrolytes are those which form ions only... 

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