Similar electrolytes

A dimensionally stable anode consisting of an electrically conducting ceramic substrate coated with a noble metal oxide has been developed (55). Iridium oxide, for example, resists anode wear experienced ia the Downs and similar electrolytic cells (see Metal anodes). 

The error due to diffusion potentials is small with similar electrolyte solutions (cj = C2) and with ions of equal mobility (/ Iq) as in Eq. (3-4). This is the basis for the common use of electrolytic conductors (salt bridge) with saturated solutions of KCl or NH4NO3. The /-values in Table 2-2 are only applicable for dilute solutions. For concentrated solutions, Eq. (2-14) has to be used. 

A similar electrolyte, containing potassium heptafluoroniobate, K2NbF7, can be used for the electrolytic reduction of niobium [37, 542 - 544]. No industrial application, however, was found for the electrolysis of niobium in fluoride-chloride melts. 

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. 

The interfaces between similar electrolytes are often called liquid junctions even though this concept includes interfaces between electrolytes that are not liquid (e.g., between gelled aqueous solutions and despite the fact that the cases 2 and 3 are also connected with liquid electrolytes). 

One of the features found at interfaces between two electrolytes (a) and ( 3) is the development of a Galvani potential, between the phases. This potential difference is a component of the total OCV of the galvanic cell [see Eq. (2.13)]. In the case of similar electrolytes, it is called the diffusion potential and can be determined, in contrast to potential differences across interfaces between dissimilar electrolytes. 

POTENTIALS BETWEEN SIMILAR ELECTROLYTES (DIFFUSION POTENTIALS)... 

Griesheim (1) An early process for producing chlorine by electrolysis, developed by Chemische Fabrik Griesheim-Elektron, in Germany, and commercialized in 1890. The electrolyte was saturated potassium chloride solution, heated to 80 to 90°C. The byproduct potassium hydroxide was recovered. The process was superseded in the United States by several similar electrolytic processes before being ousted by the mercury cell, invented by H. Y. Castner and K. Kellner in 1892. See Castner-Kellner. 

On the fundamental front, Dahn et al. successfully accounted for the irreversible capacity that accompanies all carbonaceous anodes in the first cycling. They observed that the irreversible capacity around 1.2 V follows an almost linear relation with the surface area of the carbonaceous anodes and that this irreversible process is essentially absent in the following cycles. Therefore, they speculated that a passivation film that resembles the one formed on lithium electrode in nonaqueous electrolyte must also be formed on a carbonaceous electrode via similar electrolyte decompositions, and only because... 

Similar electrolytes to Li/Cl ) cell can be used. Numerous coin-cell, spiral-wound and bobbin configurations are available, as well as three-cell-in-series prismatic 9 V [27], As with most other Li metal anode primary systems, the very low self-discharge rate affords many years of shelf life in standby usage. Therefore, applications such as smoke detectors are very popular for this system. 

Similar electrolytic oxidation of NH3 in [(bipy)2NH3Ru(/i-0)]2+ gives N 68 There are le intermediate steps beginning with [Osn(bipy)2 py NO]2+ on reduction and [Osin(bipy)2 py(NH3)]2+ on oxidation. A similar 4e electron change occurs in the reaction... 

The data of Efimov and Erusalimchik (5) shown in Fig.l give an example of the different current-voltage characteristics obtained with various resistivity n- and p-type germanium electrodes made anode in 0.1 N HC1. Brattain and Garrett (4) and others (7-10), however, found much lower saturation current densities by one to two orders of magnitude with n-type germanium made anode in similar electrolytes. Similar curves for n-type silicon would show saturation current densities in the order of microamperes per square centimeter. 

Similarly, electrolytes play a major role in the stability of the final latices. Polymerization of AH microemulsions in the absence of salt gives unstable latices, even at high surfactant concentrations. When salts with high salting-out efficiency (sodium acetate) are added to the systems, stable and clear microlatices are produced. Polymerization of microemulsions containing a polymerizable salt leads, under appropriate conditions, to the formation of stable microlatices (11,29). 

In addition to the reason for incomplete dissociation just considered, there are some cases, e.g., weak acids and many salts of the transition and other metals, in which the electrolyte is not wholly ionized. These substances exist to some extent in the form of un-ionized molecules a weak acid, such as acetic acid, provides an excellent illustration of this type of behavior. The solution contains un-ionized, covalent molecules, quite apart from the possibility of ion-pairs. With sodium chlorides, and similar electrolytes, on the other hand, there are probably no actual covalent molecules of sodium chloride in solution, although there may be ion-pairs in which the ions are held together by forces of electrostatic attraction. 

The cathodic incorporation of lithium from a solution of LiAsFg in propylene carbonate was used in the attempt [301] to obtain HTSC materials based on calcium and lanthanum niobates. The incorporation of lithium into YBCO from a similar electrolyte proceeds reversibly and ensures a discharging capacitance of the HTSC cathode high enough for application in lithium batteries [302-307]. The possibility was also reported [308-310] of incorporating lithium into BSCCO, but the capacitance values obtained are very contradictory. 

Salicyclic acid and some other acids were reduced by Na(Hg) to the aldehyde [104-107] (40-60%) in a slightly acid medium containing p-toluidine and boric acid the reaction mixture was kept slightly acid by addition of boric acid. A similar electrolytic reduction was not successful unless the mercury cathode was allowed to take up some sodium, thus making the reaction an indirect reaction [108]. 

Nanosized TiOi powders are of outstanding importance in this context. Aqueous suspensions of 30 nm particulate TiOi (mostly in the rutile form) are the active agent in many of the photocatalytic systems described by Serpone and Emetine in Chapter 5. Agglomerations of Ti02 nanoparticles into mesoporous films of pore size 2-50 nm which allow the penetration of liquid are the basis of the important dye-sensitised solar cell (DSSC) discussed by Grateel and Durrant in Chapter 8, as well as most of the hybrid devices described by Nelson and Benson-Smith in Chapter 7, and some of the ETA (Extremely Thin Absorber) cells described by Konenkamp in Chapter 6. The term eta-solar cell was actually introduced by Konenkamp and co-workers (Siebentritt et al., 1997), who had earlier used the term sensitisation cell for the same type of device (Wahi and Konenkamp, 1992). Precursors to ETA cells with liquid electrolytes as hole conductors were developed by Vogel et al. (1990), Ennaoui et al. (1992) and Weller (1993). Similar electrolytic cells with RuSa (Ashokkumar et al, 1994) and InP (Zaban et al, 1998) nanoparticle absorbers have also been demonstrated. 

The anodes that have been used include stainless steels, mild steel, lead and platinised titanium, while typical electrolytes for ferrous materials have been 0.5 M sodium hydroxide, 0.2 M sodium carbonate, 0.5 M sodium sesquicar-bonate and tap water. For bronze cannons recovered from the Mary Rose, both sodium hydroxide and sodium carbonate electrolytes were employed while pewter artefacts (plates) from the same ship were treated in similar electrolytes or in a 0.5% solution of EDTA as a sodium salt in alkaline solution. 

Lithium is extracted from LiCl in a similar electrolytic process LiCl is first obtained from spodumene by heating with CaO to give LiOH, which is then converted to the chloride. Potassium can be obtained electrol5dically from KCl, but a more efficient method of extraction is the action of Na vapour on molten KCl in a counter-current fractionating tower. This yields an Na-K alloy which can be separated into its components by distillation. Similarly, Rb and Cs can be obtained from RbCl and CsCl, small quantities of which are produced as by-products from the extraction of Li from spodumene. 

Similar electrolytic reduction 174) is achieved and Mn h.f.s. observed in reduced [(CO)4MnS2CN(C2H5)2] and [(CO)3(SPh)Mn—]2. In the latter case, the spectrum shows two equivalent manganese atoms with the remarkably small h.f.s. of 14 gauss showing that the additional electron is delocalized very considerably. The available data is given in Table XLV. There is evidence for [Cr(NO)(CN)5] - and [Mn(NO)(CN)5] -... 

Bedon, Horner and Tyree 36) obtained NaaKTiFe and KaNaTiFe by a similar electrolytic procedure, and also prepared (NH4)3TiFe by the action of excess acidified NH4F on TiCls solution. They measured the electronic spectra of these salts between 5 and 50 K. in KCl and KBr discs, and these results together with the magnetic moments at 293 °K are shown in Table 2 (i). For the Ti + ion the single d—d band expected... 

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