Batteries standard hydrogen electrode

Figure 2 illustrates the resulting situation. Due to the strong acidic solution in the battery, it corresponds lo Fig. 1 for small pH values, but here the electrode potential is drawn on the vertical axis. The values are referred to the above-mentioned standard hydrogen electrode. To enlarge the scale, the range between 0 and 1.2 V is omitted. 

The principle of the rechargeable Li-battery is illustrated in Figure 28(a), as it was originally conceived. The preferred anode is Li, the most electropositive (-3.04 V) versus standard hydrogen electrode as well as the lightest metal, which on discharge will donate an electron according to... 

All equilibrium potentials are referred to a standard hydrogen electrode. The Hg Hg2S04 electrode is widely used in lead-acid battery investigations. This electrode has a potential which is 0.620 V more positive than that of the standard hydrogen electrode at pH = 0 [18]. 

Several significant electrode potentials of interest in aqueous batteries are listed in Table 10.2 these include the oxidation of carbon and oxygen evolution/reduction reactions in acid and alkaline electrolytes. For example, for the oxidation of carbon in alkaline electrolyte, P at 25 °C is —0.780 V vs SHE (standard hydrogen electrode) or —0.682 V (vs Hg/HgO reference electrode) in 0.1 mol CO, at pH = 14. Based on the standard potentials for carbon in aqueous electrolytes, it is thermodynamically stable in water and other aqueous solutions at a pH less than about 13, provided no oxidizing agents are present. 

Briefly describe each of the following ideas, methods, or devices (a) salt bridge (b) standard hydrogen electrode (SHE) (c) cathodic protection (d) fuel cell. Explain the important distinctions between each pair of terms (a) half-cell reaction and overall cell reaction (b) voltaic cell and electrolytic cell (c) primary battery and secondary battery (d) Eceii and E°en. 

The mercurous sulfate [7783-36-OJ, Hg2S04, mercury reference electrode, (Pt)H2 H2S04(y ) Hg2S04(Hg), is used to accurately measure the half-ceU potentials of the lead—acid battery. The standard potential of the mercury reference electrode is 0.6125 V (14). The potentials of the lead dioxide, lead sulfate, and mercurous sulfate, mercury electrodes versus a hydrogen electrode have been measured (24,25). These data may be used to calculate accurate half-ceU potentials for the lead dioxide, lead sulfate positive electrode from temperatures of 0 to 55°C and acid concentrations of from 0.1 to Sm. 

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