Amalgam cells

TABLE 17.5. Cell Potentials for Indium Amalgam Cell at 25.0 C... 

TABLE 19.7. Potentials for AgCl, Na(amalgam) Cells at Several Temperatures... 

The activity ratio can be here replaced by the corresponding concentration ratio in sufficiently diluted amalgams. It follows from this equation that the EMF of the concentration amalgam cell does not depend on the ionio activity in the solution. 

Fig. 99, Diagrammatic representation of electrolyzer and decomposition trough. Z — Current source, E% — Electrolyzer, 12 — Decomposition trough, A - Graphite anode, K — Graphlto grid, Ei — Sodium chloride decomposition voltage, Et — Amalgam cell voltage.

Amalgam Cells.—If the electrolyte in the concentration cell without transference is a salt of an alkali metal, e.g., potassium chloride, it is necessary to set up some form of reversible alkali metal electrode. This is achieved by dissolving the metal in mercury, thus forming a dilute alkali metal amalgam which is attacked much less vigorously by water than is the metal in the pure state." The amalgam nevertheless reactia with water to some extent, and also with traces of oxygen that may be... 

Amalgam cells are utilized for the study of alkali hydroxides, e.g.,... 

The amalgam cells consist of slightly inclined steel troughs, over the bottoms of which flow a thin mercury layer, which absorbs the sodium and acts as the cathode. Horizontal anodes adjustable in height at which chlorine is produced are incorporated into the lid of the cells. The chlorine is drawn off upwards through gas extraction slits. 

A single amalgam cell is 0.8-2-m broad and has a length of 7-14 m. The total surface of the electrodes amounts to 30 m2, the current density can be as high as 15kAm-2. This means 450 kA in total, corresponding to a production of 13 tons of chlorine per cell in a day. 

Commercial amalgam cells are strictly monopolar, and diaphragm cells exist in monopolar and bipolar variety. This holds for membrane cells, and having presented a monopolar industrial diaphragm cell as... 

Amalgam Cell Starting with the chlorine electrode, the reversible standard potential is +1.37 V (all potentials are given versus NHE), due to the sodium concentration of 6 mol L-1 we have to note +1.33 V. The current-overpotential curve represents an unhindered process... 

Production of Alcoholates, Poly-olates, and Other Chemicals from Alkali Amalgam If the decomposer of an amalgam cell is fed with methanol instead of water, Eq. (3) will be replaced as follows... 

Consider equations (38.33) and (38.24) and hence indicate how ai/Ni for mercury could be determined directly, by a graphical method, from the e.m.f. data on the thallium amalgam cells in Table XXVII. 

F. Hine and A.J. Acioli Maciel,... the Amalgam Cell and the Membrane Cell Processes for Chloralkali Production,/. Appl. Electrochem. 22, 699-704 (1992). 

Amalgam Cells. F6r the determination of activity coefficients of electrolytes the method depending upon the measurement of the potentials of concentration cells without transference has already been discussed in Chapter 6. Two examples of such cells were mentioned. These were the following ... 

Figure 6. Flowsheet and material balance in the amalgam cell plant.

The standard potential of Na/Na+ at 25°C is -2.7142 V and the potential of the Na/Na amalgam cell is -0.75852 V when the mole fraction of sodium in the amalgam is unity. Hence, the standard electrode potential for the reaction... 

The design used in the industry is the tower-type decomposer wherein graphite lumps (—10 mm diameter) are packed in the tower and sodium amalgam is flashed from the top of the tower. The denuded mercury is recycled to the amalgam cell and caustic soda... 

Since we know the values for the silver-silver halide electrodes versus the standard hydrogen electrode (see above), we can easily set up a series of standard potentials vs. H2 assuming (H+ H2) = 0.0 V. Recently Scrosati et made measurements on double amalgam cells in pure methanol. Their results for the alkali metal chlorides and bromides are in good agreement with others but the iodide systems appear to involve some error since a value of --0.2993 V is obtained for of cell (Vc). Table 2.7.2 lists the standard potentials of the alkali-metal electrodes. 

Pavrov et have reported results on double amalgam cells of... 

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