The electrolysis of solutions

When sodium chloride dissolves in water, its ions become free to move. So the solution can be electrolysed. 

In the laboratory, the electrolysis is carried out with graphite or platinum electrodes, and a concentrated solution of the salt. You might expect sodium and chlorine to be obtained at the electrodes. But this does not happen— hydrogen and chlorine are obtained instead. 

When a concentrated solution of sodium chloride is electrolysed, using graphite or platinum electrodes, hydrogen and chlorine are obtained at the electrodes. 

The apparatus is shown on the right. It allows the gases to be collected as they bubble off. Note the symbol for the battery. 

Where the hydrogen comes from The hydrogen can only 

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Kolbe reaction The pre >aration of saturated or unsaturated hydrocarbons by the electrolysis of solutions of the alkali salts of aliphatic carboxylic acids. Thus, ethanoic acid gives ethane,... 

Methods have been developed for perchloric acid synthesis which involve the electrolysis of solutions containing hydrogen chloride or molecular chlorine. These processes occur at high anode potentials (2.8 to 3.0 V vs. SHE), when oxygen is evolved at the anode in parallel with perchloric acid formation. The current yields of perchloric acid will increase considerably when the reaction is conducted at low temperatures (e.g., 20°C). 

More particularly, a serious breakthrough was achieved in the methods of electrochemical calorimetty. Initial conclusions as to anomalous heat evolution during the electrolysis of solutions prepared with heavy water were caused by an incorrect formulation of control experiments in light water. In fact, none of the communications confirming anomalous heat evolution have been free of procedural errors, so that one cannot even discuss a sporadic observation of this effect. In contrast to all other experimental manifestations, heat evolution is indicative of any possible nuclear transformation, which implies that in its absence, neither reaction (33.4.1) nor reaction (33.4.2) can be suggested to occur. 

Case II Reversible or Ouasi-Reversible Redox Species. If the tip-sample bias is sufficient to cause the electrolysis of solution species to occur, i.e., AEt > AEp, ev, the proximity of the STM tip to the substrate surface (d < 10 A) implies that the behavior of an insulated STM tip-substrate system may mimic that of a two-electrode thin-layer cell (TLC)(63). At the small interelectrode distances required for tunneling, a steady-state concentration gradient with respect to the oxidized (Ox) and and reduced (Red) electroactive species should be established between the tip and the substrate, and the resulting steady-state current will augment that present as a result of the convection of electroactive species from the bulk solution. In many cases, this steady state current is predicted to overwhelm the convective currents, so this situation is of concern when STM imaging under electrochemical conditions (64). 

The principal characteristics of this method are the electrolysis of solutions of organic compounds using electrodes of platinum or graphite at anode potentials below those which could give rise to the evolution of elemental fluorine. 

Metal is plated out in the electrolysis of solutions of metal salts, other than those of the alkali and alkaline earth metals (and iron and aluminum). For example, in the electrolysis of a ZnCl2 solution, we would obtain metallic zinc,... 

The electrolysis of solutions of organic compounds in anhydrous hydrogen fluoride under conditions where no free fluorine is produced. 

G. Janeceks observed that spontaneously inflammable phosphine is evolved during the electrolysis of solutions of the metaphosphates. S. Arrhenius, in his thesis Recherches sur le conductibUite galvanique des electrolytes (Stockholm, 1884), gave measurements of the electrical resistance, and the electrical conductivity of the acid. E. B. R. Prideaux found the meta-acid has a greater conductivity than... 

A modification of the electrolytic method involves the electrolysis of solutions containing both the metallic and the mercuric ions. This procedure should possibly lead to the deposition of amalgams of varying composition, but no extensive study of this sort has ever been reported. Bismuth and copper amalgams have been prepared in this manner. 

This theory accounts for the dependence between the current efficiency and the concentration of HSO ions present in the solution. It cannot explain, however, why the yields at the electrolysis of solutions of sulphates, in which the concentration of HSO ions is very low, are even greater than when electrolysing solutions of sulphuric acid alone or its mixture with a sulphate. This deficiency is not found in the recent explanation of the reaction mechanism, according to which the sulphate ions SO - are primarily oxidized by hydrogen peroxide or by hydroxyl radicals formed, according to equations ... 

In the electrolysis of solutions of alkali hydroxides under suitable conditions, hydrogen peroxide is produced at the anode by the combination of the discharged hydroxyl ions. 

In contradistinction to ozone, hydrogen peroxide is not produced during the electrolysis of solutions of fluorides.4... 

The electrolysis of solutions of lithium chloride in various solvents, such as water, alcohols, glycerol, and phenol, has been investigated by Patten and Mott.9... 

Preparation.—Being very sensitive to rise of temperature, the isolation of the ammonium radical by the electrolysis of solutions of ammonium salts in liquid ammonia is probably precluded by the thermal effect of the current. Its formation by the interaction of well-cooled ammonium chloride and a solution of potassium in liquid ammonia at —70° C. is indicated by a deficit of as much as 65 per cent, in the volume of the hydrogen evolved.1... 

In the electrolysis of solutions of M(S04)2 dHyO, protons move toward the cathode and the metal to the anode, so these compounds can be formulated as H2[M0(S04)2] -3H20 (disulfatozirconic and -haftiic acids). The reaction of sodium acetate with Zr0Cl2-8H20 yields diacetatozirconic acid (equation 9). They do not precipitate with acid dyes, and they react with anion exchange resins rather than with their cation exchange counterparts. 

Electrochemical Behaviour.— The electrolysis of solutions containing uranium compounds has not been fully investigated, but in generM the product at the cathode appears to consist of hydrated oxides in various stages of oxidation. This is the case even when a... 

Another general method for preparation of amalgams consists of the electrolysis of solutions ofthe respective metal salts in cells comprising an Hg cathode. The concentrations of the respective metals in the amalgam reach very high levels so that solid phases may separate. The method is applicable even to metals with extremely low solubility in Hg (for example, Fe) in this case, the method gives suspensions of the metal in Hg which exhibit behavior very similar to that of true amalgams (see Table 7). 

This second part investigates the electrolysis of solution S2 with a supporting electrolyte. The composition is the following, as indicated at the beginning of this appendix 10 mol L AgN03 + 10 mol L KNO3 aqueous solution. 

In the electrolysis of solutions of salts of the alkali metals, Favre found a much smaller electromotive force required than that calculated from the heat of formation of the salt the electromotive force of the Smee cell corresponds with 1 50 kcal., the heat of formation of sulphate of potash is io 6o, hence seven cells should be required, but five were sufficient. Favre assumed that the salts were electrolysed into cation and anion (e.g. and SO4 ") but there was a secondary reaction of the metal and water which was electromotively active, whilst this is not otherwise true of secondary reactions. 

The electrolysis of solutions of the lower alkylmercury halides in liquid ammonia results in the deposition on the cathode of an electrically conducting solid of metallic appearance, which decomposes at room temperature into equimolar proportions of R Hg and Hg. The methyl derivative is the easiest to obtain. It was the first example of an organic metal to be described and appears to consist of MeHg cations and an equivalent number of free electrons. Its possible formulation as consisting of free radicals, or RHgHgR or amalgams of Hg -h RHg, has been excluded in various ways. 

Qualitative anticorrosive, decorative, abrasion-resistant, and heat-resistant coatings are usually obtained by the electrolysis of solutions containing coordination compounds (complexes) of metals. Electrochemical processes involving these compounds are rather complicated because they proceed through several different stages, such as the mass transfer of chemically interacting particles, adsorption, charge transfer, formation of new phases, and so on. 

As yet only one type of anodic process leading to the forma -tion of organometallic compovmds has been investigated in sufficient detail this is the electrolysis of solutions or melts of organic complex electrolytes-... 

German organic chemist. Kolbe made many important contributions to the development of organic chemistry. These included the synthesis of ethanoic acid from completely inorganic materials, the formation and hydrolysis of nitriles, the electrolysis of solutions of fatty acid salts and the synthesis of salicylic acid from phenol and carbon dioxide. In his later years his influence had a negative effect on the development of chemistry because he opposed concepts such as structure. 

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