Electromotive-force series

In the electromotive force series of the elements, silver is less noble than only Pd, Hg, Pt, and Au. AH provide high corrosion resistance. Silver caimot form oxides under ambient conditions. Its highly reactive character, however, results in the formation of black sulfides on exposure to sulfur-containing atmospheres. 

This series is called the electromotive-force series because the tendency of one metal to reduce ions of another can be measured by setting... 

The standard reference point in the electromotive-force series is the hydrogen electrode, which consists of gaseous hydrogen at 1 atm bubbling over a platinum electrode in an acidic solution (Fig. 12-6). 

Oxidation number the way to balance oxidation-reduction reactions. Electromotive-force series of the elements. 

After reference to the electromotive-force series of the elements, would you expect potassium to reduce zinc ion in significant amount Nickel to reduce magnesium ion Silver to reduce lead ion Lead to reduce silver ion Barium to reduce gold ion ... 

Let us now consider the reaction at the cathode of cell A. At this electrode metallic silver is deposited. The alternative possibility, that gaseous hydrogen be produced from water, is indicated not to occur because silver lies below hydrogen in the electromotive-force series of the elements, given in Table 12-1. The cathode reaction is accordingly... 

This reaction is expected, rather than the liberation of hydrogen, because copper, like silver, lies below hydrogen in the electromotive-force series. One gram-atom of copper, 63.57 g, would hence be deposited on the cathode by 2 faradays of electricity, and 6.357 g is deposited by 0.200 faraday. 

The solution of copper by hot convcentrated sulfuric acid illustrates a general reaction—solution of an unreactive metal in an acid under the influence of an oxidizing agent. The reactive metals, above hydrogen in the electromotive-force series, are oxidized to their cations by hydrogen ion, which is itself reduced to elementary hydrogen for example,... 

Mercury is the only metal which is liquid at room temperature (cesium melts at 28.5" C, and gallium at 29.8°). It is iinreacrive, being below hydrogen in the electromotive-force series. Because of its unreactivity, fluidity, high density, and high electrical conductivity it finds extensive use in thermometers, barometers, and many special kinds of scientific Apparatus. 

Polyaniline s metallic character, its position just below silver towards the noble-metal end of the electromotive force series, and its redox behaviour mentioned above, also make it possible to use a polyaniline coating to protect metals against corrosion. Our investigations show that the plastic removes electrons from the metal and is thereby reduced, while iron, for example, is oxidised to Fe203, This oxide layer is not rust (which consists of a loose mixture of various oxides and hydroxides), but functions as a protective passivating layer, in other words prevents further... 

Equation (5) or (11) can be applied directly to half-cell reactions such as (6) and (7) and the resulting potentials obtained will be identical to those obtained from the overall reactions (9) and (10) because of the definition of the SHE as the universal standard. A selection of standard potentials of half-cell reactions is shown in Table 1 [5]. By international convention, electrode reactions in thermodynamic tables are always written as reduction reactions, so the more noble metals have a positive standard potential. Lists such as that in Table 1 are also called electromotive force series or tables of standard reduction potentials. 

A list of standard potentials of electrode reactions, organized by numerical value (Table 2.8), is referred to as series of standard potentials of eleelrode reactions or electromotive force series. A more complete set of such data can be found in reference [6],... 

Flengas, S.N., and Ingraham, T.R. (1959). Electromotive force series of metals in fused salts and activities of metal chlorides in 1 1 molar KCl-NaCl soXvXxons, J.Electrochem.Soc. 106, 84-91. Tumidajski, P.J., and Flengas S.N. (1991). Potential measurements of reactive metal chloride in alkali halide solution. W.CYiiormwm, J.Electrochem.Soc. 138, 1659-1665. 

Smirnov, M.V., and Potapov, A M. (1994) Redox potentials and electronic absorption spectra of dilute solutions of nickel and chromium chlorides in molten alkali chlorides, Electrochim.Acta, 39, 143-149. Laitinen, H.A., Liu, C.H. (1958). An electromotive force series in molten lithium chloride-potassium chloride eutectic, J.Amer.Chem.Soc, 8, 1015-1020. 

A limited amount of electroanalytical work has been done in sulfate melts. The oxygen electrode has been mentioned above for alkaline melts. In 1961, Liu (77,78) applied potentiometry, chronopotentiometry and coulometric titrations in lithium sulfate-potassium sulfate melts at 625°C using a silver reference electrode. An electromotive force series of limited scope and... 

Melts containing magnesium chloride and alkali metal chlorides have received study going back to 1950 (80). An electromotive force series has been described by Gaur and Behl (26). 

A wide variety of data is available to characterize the nature of the reaction between engineering materials and their chemical environments (Shackelford, Alexander, and Park, 1994). Perhaps no such data are more fundamental and practical than the electromotive force series of metals shown in Table 2.29. The voltage associated with various half-cell reactions in standard aqueous environments are arranged in order, with... 

Electromotive force series Systematic listing of half-cell reaction voltages. 

Would you expect zinc to reduce cadmium ion (Refer to the electromotive-force series.) Iron to reduce mercuric ion Zinc to reduce lead ion Potassium to reduce magnesium ion ... 

The metal is reactive (note its position in the electromotive-force series), and when strongly heated it burns rapidly in air or oxygen. Aluminum dust forms an explosive mixture with air. Under ordinary conditions, however, aluminum rapidly becomes coated with a thin, tough layer of aluminum oxide, which protects it against further corrosion. 

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