Cathodic solution

Normal ceU voltages are ca 0.2 V. The power consumption is correspondingly very smaH, and electrorefining is much less sensitive to the cost of electric power than other electrometaHurgical processes. When a diaphragm is used to separate the anodic and cathodic solutions, the ceU voltage increases up to ca 1.2 V, and the power consumption rises accordingly. 

The water concentration in the paint and in the paint film has been determined using a Mitsubishi moisture meter. The anode cell was filled with Karl-Flscher reagent and the cathode cell with a mixture of pyridine, formamlde and Karl-Flscher reagent (70/30/6Z (v/v)). Paint samples were injected directly into the cathode solution. 

After flash-off periods at defined relative humidities, the paints were scraped from the panels and dissolved in the cathode solution. 

Figure 9.5 Generation of a pH gradient by ampholytes within a capillary flanked by an acid as anodic solution and base as cathodic solution. Ampholyte solutions are composed of high numbers of low-molecular weight amphoteric electrolytes (from which the name is derived) with slightly different pi values. Because ampholytes possess buffering capacity, they maintain a pH value in the specific area occupied by the different molecular species. The sample, which is also amphoteric, focuses in between ampholytes with higher and lower pi. To achieve resolution, there must be at least one ampholyte with a pi intermediate to the two sample components of interest.

Use a suitable apparatus connected with a recirculating temperature-controlled water bath set at 10°C and gels for isoelectric focusing with a pH gradient of 3.5-9.5. Operate the apparatus in accordance with the manufacturer s instructions. Use as the anode solution phosphoric acid R (98 g/1 H3PO4) and as the cathode solution 1 M sodium hydroxide. Samples are applied to the gel by filter papers. Place sample application filters on the gel close to the cathode. 

EMF isn t constant over the life of a voltaic cell, because the concentrations of the aqueous solutions are in flux. The anode solution s concentration increases over time, and the cathode solution s concentration decreases, changing the value of the reaction quotient and therefore the EMF. 

We illustrate the coulometric procedure in Figure 17-28, in which the main compartment contains anode solution plus unknown. The smaller compartment at the left has an internal Pt electrode immersed in cathode solution and an external Pt electrode immersed in the anode solution of the main compartment. The two compartments are separated by an ion-permeable membrane. Two Pt electrodes are used for end-point detection. 

In a typical procedure, the main compartment in Figure 17-28 is filled with anode solution and the coulometric generator is filled with cathode solution that may contain reagents designed to be reduced at the cathode. Current is run until moisture in the main compartment is consumed, as indicated by the end-point detection system described after the Example. An unknown is injected through the septum and the coulometer is run again until moisture has been consumed. Two moles of electrons correspond to 1 mol of H20 if the I2 H20 stoichiometry is 1 1. 

In another paper, they confirmed that the absorbance of solutions of NaB(CaHs)4 and KB(C6He)4 and of NaAl(C2H5)4 was strictly proportional to the number of electrons transfer at the electrode. And from the observation that mixing of the anode and cathode solutions resulted in a destruction of the living ends, they reversed the polarity of the electrodes and found a stoichiometric destruction of the living ends of a-methystyrene tetramer and a decrease in absorbance directly dependent on the charge transferred 13). Exactly same quantity of charge was... 

Repeat step 6 with a second IEF electrode strip using IEF cathode solution. 

If the anode and cathode solutions are mixed, the H+ and OH- ions react to form... 

Of the older methods for the preparation of periodic acid, the most satisfactory for obtaining large quantities is the electrolytic oxidation of iodic acid at an anode of platinum plated with lead dioxide, the cathode solution being dilute nitric acid.1 The iodic acid for this preparation is conveniently prepared by the electrolytic oxidation of iodine.1 However, periodic acid prepared in this way often contains... 

The OH" ions, which thus accumulate in the cathode compartment, are balanced by the Na+ ions, which are brought up by the electrolytic conduction. The commercial sodium hydroxide is obtained by evaporating the cathode solution to a high concentration of NaOH, in which NaCl is insoluble. The crystals of NaCl are removed in centrifugal filters, and the purified solution is evaporated until molten NaOH is left. This is poured into molds and allowed to solidify. If the total sodium hydroxide could be recovered, 40 grams would be realized for each faraday. It is the object of this experiment to determine what percentage of this ideal yield can be obtained in a simple cell. 

Now carefully remove the anode from the coulometer, and set it in a test tube full of distilled water. Be careful not to bruise it. Then rinse it with alcohol and, after it has dried, weigh it. Return the CuSCh solution to a bottle marked Used CuSCh Solution. Titrate the cathode solution with the standard acid prepared in Experiment 6, and thus determine the number of equivalents of NaOH produced in the cathode compartment. 

Diphenyl ditellurium was electrochemically reduced to benzenetellurolate in acetonitrile with sonication in anH-type cell. Tetrabutylammonium hexafluorophosphate served as the electrolyte. The cathode was a cylindrical graphite cloth and the anode a platinum grid. The cathodic solution was purged with argon. The potential had to be changed from — 1.20 to — 2.35 V during the reduction1-3. 

Lob,3 convinced of the futility of thus being able to obtain a good yield of benzidine by a direct reduction of nitrobenzene in acid solution, sought to carry out the benzidine process by a careful realization of the conditions theoretically required— primary preparation of azoxy- or azobenzene in the best quantitative yields, i.e. in electrolytes, containing alkali or alkali-salt, then reducing these products in acid solution. Two processes thus resulted. In the first one the electrolytic reduction was carried out to azobenzene in alcoholic-alkaline solution, then the cathode solution was acidified with sulphuric acid, and the further reduction and molecular rearrangement combined in one operation. The second process, which was... 

When a species reduced at a cathode is oxidized at an anode, and vice versa, a two-compartment cell, namely a divided cell like an H-type cell (Figure 8.3) with a sintered glass diaphragm or an ion-exchange membrane should be used in order to prevent mixing of both anodic and cathodic solutions. To decrease the ceU voltage (voltage between an anode and cathode), the distance between both the electrodes should be kept as small as possible. 

Macinnes and Dole [/. Am, Chem, Soc, 53, 1357 (1931)] electrolyzed a 0.5 N solution of potassium chloride, containing 3.6540 g. of salt per 100 g. solution, at 25 using an anode of silver and a cathode of silver coated with silver chloride. After the passage of a current of about 0.018 amp. for approximately 26 hours, 1.9768 g. of silver were deposited in a coulometer in the circuit and on analysis the 119.48 g. of anode solution were found to contain 3.1151 g. potassium chloride per 100 g. solution, while the 122.93 g. of cathode solution contained 4.1786 g. of salt per 100 g. Calculate the values of the transference number of the potassium ion obtained from the anode and cathode solutions, respectively. 

Jones and Bradshaw [J. Am, Chem, Soc. 54, 138 (1932)] passed a current of approximately 0.025 amp. for 8 hours through a solution of lithium chloride, using a silver anode and a silver chloride cathode 0.73936 g. of silver was deposited in a coulometer. The original electrolyte contained 0.43124 g. of lithium chloride per 100 g. of water, and after electrolysis the anode portion, weighing 128.615 g., contained 0.35941 g. of salt per 100 g. water, while the cathode portion, weighing 123.074 g., contained 0.50797 g. of salt per 100 g. of water. Calculate the transference number of the chloride ion from the separate data for anode and cathode solutions. 

Hammett and Lowenheim [J. Am. Chem. Soc., 56, 2620 (1934)] electrolyzed, with inert electrodes, a solution of Ba(HS04)2 in sulfuric acid as solvent 1 g. of this solution contained 0.02503 g. BaS04 before electrolysis. After the passage of 4956 coulombs, 41 cc. of the anode solution and 39 cc. of the cathode solution, each having a density of 1.9, were run off they were found on analysis to contain 0.02411 and 0.02621 g. of BaS04 per gram of solution, respectively. Calculate the transference number of the cation. 

A solution, 100 g. of which contained 2.9359 g. of sodium chloride and 0.58599 g. urea, was electrolyzed with a silver anode and a silver chloride cathode after the passage of current which resulted in the deposition of 4.5025 g. of silver in a coulometer, Taylor and Sawyer [/. Chem. Soc. 2095 (1929)] found 141.984 g. of anode solution to contain 3.2871 g. sodium chloride and 0.84277 g. urea, whereas 57.712 g. of cathode solution contained 2.5775 g. sodium chloride and 0.32872 g. urea. Calculate the true and apparent transference numbers of the ions of sodium chloride in the experimental solution. 

Cathode solution IMNaOH, for wide pH range focusing (seeNote 28). 

Prepare two electrode wit ks (0.5 cm x dth cf the gel) from the filter paper and soak one in anode solution and the other in cathode solution. Place on the gel surface (see Note 27). 

If the cell metal concentrated solution dilute solution metal is capable of yielding a current, the direction of the current must be such that the concentrated solution becomes more dilute and the dilute solution more concentrated. The positive current must therefore fiow from the dilute to the concentrated solution inside the cell, so that the electrode dipping into the concentrated solution becomes the cathode. As 1 —i/ equivalents of the electrolyte = 2(l —j/) equivalents of the ions are transferred by unit quantity of electricity from the more concentrated (cathode) solution to the more dilute (anode) solution, the E.M.F. of this concentration cell can be calculated by the same two methods (p. 354) which Helmholtz and Nemst employed in the calculation of the e.m.f. of concentration cells without transference. Thus, for dilute solutions of an w-valent metallic salt, we have the equation... 

The first experiments showed that an appreciable amount oS sodium cinnamate was transferred to the anodic compartment when the salt was electrolyzed. To avoid this the reduction was carried out in tlu presence of an excess of sodium hydroxide. The best conditions found were as follows Cathode sheet load (area 260 sq. cm.) anode, sheet lead. The cathodic solution was prepared by adding 30 grams of cinnamii acid to a warm solution of 8.1 grams of sodium hydroxide dissolved ir 400 cc. water. The solution was transferred to a porous cup, heated tsodium hydroxide in 100 cc. of warm water was then slowly added. The additio of the excess of alkali caused the precipitation of a part of the sodiuiv-cinnamate. The solution was stirred during the electrolysis until th( suspended matter dissolved. The temperature was kept at about 60° C A current density of 5.7 amperes per sq. dm. was maintained unti 90.7 per cent of the theoretical current had passed it was then reduced to 2.4 amperes per sq. dm. until 9.8 per cent excess had passed. Thi current efficiency therefore was 83 per cent. 

The cathodic solution was cooled in ice water, and a large execs-of concentrated hydrochloric acid was added. An oil separated, whicl was filtered off after it had solidified. The hydrocinnamic acid melted at 46.7° to 48° C. The yield was 91 per cent of the theoretical. Source Norris 1925 References Marie 1903, Ingersoll 1925, 1928... 

Yu, X., and Licht, S. 2008. Recent advances in synthesis and analysis of Fe(VI) cathodes Solution phase and solid-state Fe(VI) syntheses, reversible thin-fihn Fe(VI) synthesis, coating-stabilized Fe(VI) synthesis, and Fe(VI) analytical methodologies. Journal of Solid State Electrochemistry 12, 1523-1540. 

P-Lactams have been synthetized in elevated yields (59-91%) avoiding the use of VOCs as well as of bases. After the workup of the cathodic solution, the ionic liquid was recovered and reused for five subsequent syntheses. In each case, P-lactams were isolated without any decrease of the yields (e.g. yield 82%, 94%, 92%, 89%, 93%) [112]. 

Surface treatment has also been employed to generate membranes with improved hydroxide ion rejection capability for chlor-alkali applications. In this procedure, one surface of a sulfonyl fluoride XR resin film is treated with an amine such as ethylene-diamine. After hydrolysis, a thin barrier layer of weakly acidic sulfonamide exchange sites is formed. When this treated surface faces the cathode solution, improved hydroxide rejection is realized in a membrane chlor-alkali cell. 

Another governing relationship, however, is Ohm s law, which leads to a dependency of the corrosion current on both the polarization characteristics of the anodic and cathodic reactions and on the total electrical resistance of the system, Rtotal. Rtotal includes the resistance in the metal between anodic and cathodic areas, RM a metal junction resistance if different metals are associated with the two areas, Rac any anode- or cathode-solution interface resistance, Rai and Rci and the solution resistance, Rs. The latter depends on the specific resistivity or conductivity of the solution and the geometry of the anode-solution-cathode system. 

---