Silver-hydrogen cells

Hydrogen-silver cells are attractive (apart from cost) since the energy density is higher than the hydrogen-nickel analogue. The cell is... 

The hydrogen half-cell is not very convenient for routine laboratory usage—indeed, 1 m H+ (corresponding to a pH of 0 ) and 1 atm H2 (explosive) are dangerous. Hence, secondary standards are used, e.g., mercury/mercurous (calomel) or silver/silver chloride electrodes, which have midpoint redox potentials of 0.244 V and 0.222 V, respectively. 

In order to determine Ki a serie.s of cells of the type depicted above, in which the ratio of mi to m2 is kept constant but the amounts of RHjCl-and of RH= are varied, are set up and the e.m.f. s (E) measured. The value of for the hydrogen-silver chloride cell is known, and so the left-hand side of equation (4) can be evaluated the Debye-Hiickel factor A is 0.509 at 25. In calculating the ionic strength of the solution the... 

A galvanic cell is constructed using a standard hydrogen half-cell (with platinum electrode) and a half-cell containing silver and silver chloride ... 

The name and symbol come from Spanishplatina, meaning silver. Although this metal was used in pre-Columbian South America, it was identified by a European as a unique mineral in 1557 by Julius Caesar Scaliger (1484-1558). Platinum was described in 1745 by Antonio de Ulloa (1716-1795), but he was prevented from publishing until 1748. Charles Wood independently described the metal in 1741, but it was not identified as a new element until 1750, when it was studied by William Watson (1715-1787). Platinum is very rare and is extensively used as jewelry, but in recent years it has been increasingly used in the electronics industry and as a catalyst, both for scientific research and in commercial applications such as antipollution devices (catalytic converters) and hydrogen fuel cells. 

The accepted primary reference electrode is the hydrogen half cell described in association with Fig.2.1 (Ref 5). It consists of platinum (which serves as an inert conductor) in contact with a solution at 25 °C, saturated with hydrogen gas at one atmosphere pressure, and containing hydrogen ions at pH = 0 (aH+ = 1). In practice, the major use of the standard hydrogen electrode (SHE) is for calibration of secondary reference electrodes, which are more convenient to use. Two common reference electrodes are the calomel or mercury/saturated-mercurous-chloride half cell with a potential of +241 mV relative to the SHE and the sil-ver/saturated-silver-chloride half cell with a relative potential of+196 mV. Both of these electrodes are saturated with potassium chloride to maintain a constant chloride and hence metal-ion concentration. 

I-or a sulfur determination, the sample is combusted in an oxygen atmosphere in a tube packed with tung-sten(Vf) oxide or copper oxide. Water is removed by a dehydrating reagent located in the cool zone of the same tube. The dry sulfur dioxide is then separated and determined by the differential signal at what is normally the hydrogen detection cell. In this instance, however, the sulfur dioxide is absorbed by a silver oxide reagent. 

The potential of the standard hydrogen half-cell can be set at zero since only differences are measured, and the hydrogen value always cancels in these differences. In the cell above, the activities of H2, Haq, and Ag° are 1, as defined for the standard hydrogen half-cell and a pure solid. Putting these into the Nernst expression above shows why we can call this the half-cell potential for the silver couple ... 

The Zinc-Copper Cell 21-10 The Copper-Silver Cell Standard Electrode Potentials 21-11 The Standard Hydrogen Electrode 21-12 The Zinc-SHE Cell 21-13 The Copper-SHE Cell 21-14 Standard Electrode Potentials 21-15 Uses of Standard Electrode Potentials 21-16 Standard Electrode Potentials for Other Half-Reactions 21-17 Corrosion 21-18 Corrosion Protection... 

AUcaline fuel cells (AFCs, hydrogen-fuelled cells with an alkaline liquid electrolyte such as KOH(aq)) are the best performing of all known conventional hydrogen-oxygen fuel cells operable at temperatures below 200 C. This is due to the facile kinetics at the cathode and at the anode cheaper non-noble metal catalysts can be used (such as nickel and silver [3,4]), reducing cost. McLean et al. gave comprehensive review of alkaline fuel cell technology [5]. The associated fuel cell reactions both for a traditional AFC and also for an AMFC are ... 

An electrode is prepared by dipping a silver strip into a solution saturated with silver thiocyanate, AgSCN, and containing 0.10 M SCN. The emf of the voltaic cell constructed by connecting this electrode as the cathode to the standard hydrogen half-cell as the anode is 0.45 V. What is the solubility product of silver thiocyanate ... 

The electrochemical and technological laboratory which studied and developed oxygen-hydrogen fuel cells was in this production plant. Raney nickel and silver were used as catalysts. 

From the theory of the electrochemical cell, the potential in volts of a silver-silver chloride-hydrogen cell is related to the molarity m of HCI by the equation... 

Figure 3-1 Voltage Measurements on a Silver-Silver Chloride, Hydrogen Cell at 298.15 K. The contribution of the Standard Hydrogen Electrode is taken as zero by convention.

Fig. 24. Silver—hydrogen cell discharge characteristics where ( ) represents a 0.5 h rate at 4 A or 80 mA/cm (—...

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