Galvanic cells temperatures, table

From the figures given in Table IV the increase of entropy during the reaction is 8.5 units. As a test of the third law of thermodynamics this value may be compared with a determination of the entropy change of this reaction made by Gerke,21 from the potentials of galvanic cells, in a research already referred to. He measured the potential, E, and the change of the potential with temperature, AE/AT, of cells of the type... 

The Variation of the Standard Potentials of Some Electrodes with the Temperature. In a number of cases the standard potentials of galvanic cells without liquid junctions have been determined over a range of temperatures. From these determinations it has been possible to prepare Table V, which gives the standard potentials of a number of electrodes at intervals of 12.5° from 0° to 50°. Some slight adjustments, of the order of 0.2 millivolt, of the original data have been necessary to bring the figures into accord with the Ho values at 25° adopted in this book. A more complete table of standard potentials of the elements at 25° will be found at the end of Chapter 14. 

Therefore the setup where the dissolution reaction is followed by potentiometric measurements of the pertinent H -concentration within the galvanic cell (glass electrode solution salt bridge reference electrode) is an optimal system for solubility measurements. This method is called potentiometric method of solubility measiuements ( Potentio in Table 1.1). An example of such measurements could be tiiat of solubility of metal oxides at temperatures up to 300°C performed in ORNL using simultaneously sampling method and the hydrogen-electrode concentration cell (HECC). The details of such measurements and experimental setup can be found in Chapter 3 in this Book. 

FIGURE 4.3 Temperature dependence of the standard OCP for Hj/Oj, C/Oj, and H2/CI2 fuel (galvanic) cells. The calcnlations were carried out using the data from [Chapter 10, Table 10.4]. 

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