Cell, galvanic Volta

The dual aspect of the electrochemical cell—galvanic or electrolytic—was recognized shortly after the cell s discovery in 1800 by Alessandro Volta. Volta constructed a battery of cells consisting of a number of plates of silver and zinc that were separated from one another by porous strips of paper saturated with a salt solution. By 1807, Sir Humphry Davy had prepared elemental sodium and potassium by using a battery to electrolyze their respective hydroxides. But, the underlying scientific basis of the electrochemical cell was not understood. Michael Faraday s research showed a direct quantitative relationship between the amounts of substances that react at the cathode and the anode and the total electric charge that passes through the cell. This observation is the substance of Faraday s laws, which we state as follows ... 

The galvanic cell invented by Volta in 1800 was composed of two dissimilar metals in contact with mois-... 

Italian physicist Alessandro Volta demonstrates the galvanic cell, also known as the voltaic cell. 

In addition, this review has been prepared to promote the term voltaic cell in honor of Alessandro Volta, the inventor of the pile, i.e., an electrochemical generator of electricity. Up to now this name has been used in only a few papers. This term is a logical analogue to the term galvanic cell, particularly in discussions of Volta potential and Gal-vani potential concepts. 

The basic principle of every measurement of the Volta potential and generally of the investigations of voltaic cells too, in contrast to galvanic cells, may thus be presented for systems containing metal/solution (Fig. 2) and liquid/liquid interfaces (Fig. 3), respectively. This interface is created at the contact of aqueous and organic solutions (w and s, respectively) of electrolyte MX in the partition equilibrium. Of course, electrolyte MX, shown in Fig. 2 and other figures of this chapter, may be different in organic (s) and aqueous (w) phases. 

Knowledge of the Volta potential of a metal/solution interface is relevant to the interpretation of the absolute electrode potential. According to the modem view, the relative electrode potential (i.e., the emf of a galvanic cell) measures the value of the energy of the electrons at the Fermi level of the given metal electrode relative to the metal of the reference electrode. On the other hand, considered separately, the absolute value of the electrode potential measures the work done in transferring an electron from a metal surrounded by a macroscopic layer of solution to a point in a vacuum outside the solotion. ... 

It will be assumed that the interactions between each of metals (1) and (2) and the corresponding surface layers of the electrolyte solution are approximately identical, and also that specific adsorption of ions does not occur in the system being considered. In this case the values of the expressions in the last two sets of brackets in Eq. (9.10) become zero, and from (9.10) and (9.11) an important relation is obtained which links the OCV of galvanic cells with the Volta potential ... 

This expression explains the qualitative agreement found to exist between the OCV values of galvanic cells and the Volta potentials of the corresponding metal pairs. But through terms and it also explains why OCV values depend on solution composition. All parameters of this equation can be measured experimentally. 

Galvanic cells are named after the Italian doctor Luigi Galvani (1737-1798), who generated electricity using two metals. These cells are also called voltaic cells, after the Italian physicist Count Alessandro Volta (1745-1827), who built the first chemical batteries. 

Here we investigate some of the properties of galvanic cells, cells used to produce an electric potential. Luigi Galvani discovered the first such cell by accident in 1791. Following Galvani s discovery, Alessandro Volta developed a practical cell in 1800, and it was Volta s cell that led to the work of Davy and Faraday. 

The existence of a contact potential between two different metals was recognized over a century ago by Volta, who ascribed the origin of the electromotive force of galvanic cells to it. This point of view receded somewhat into the background in the later decades of last century, but is now re-established, as will be seen in 5. It is not very easy to demonstrate the existence of this contact potential and its actual value depends very much on the cleanliness of the surface indeed without very careful cleaning of the surface, and removal of surface films, which requires a high standard of vacuum technique, the true value for the clean metal can scarcely be obtained at all. 

The name galvanic cell honors Luigi Calvani (1737-1798), an Italian scientist generally credited with the discovery of electricity. These cells are sometimes called voltaic cells after Alessandro Volta (1745-1827), another Italian, who first constructed cells of this type around 1800. 

Volta s greatest contribution was, however, the discovery, in 1796. of the voltaic pile, which consisted of a series of units, each made from sheets of dissimilar metals such as zinc and silver separated by wet doth. Volta showed that metals could be arranged in au "electromotive series so that each became positive when placed in contact with the one next below it in the series. Although, as has already been mentioned, Volta considered that the source of the electric energy was at the surface of contact of, the metals, this theory was thrown in doubt when it was discovered that chemical action accompanied the operation of the pile. It is of interest that the question of the seat of the potential of the galvanic cell is not, even today, finally settled. Many improvements of the voltaic pile were made. It is, of course, the precursor of the modern galvanic cell. 

Fuel cells (FCs) are electrochemical devices that directly convert fuel energy into electricity without the need for a thermal cycle. They are essentially galvanic cells in which the electrodes only collect and convey electrical charges, but (unlike in the Volta pile and all other electric cells and batteries) they do not participate in the electrochemical reaction, since they are chemically and electrochemically inert conductors (amorphous carbon, sintered nickel oxide, etc.). 

Just a few months after the appearance of the Volta pile it was found that the electric current can exert a chemical action. As early as May of 1800, Nicholson and Carlisle carried out water electrolysis. In 1803 the processes of metal electrodeposition were discovered. In 1807 Davy for the first time isolated alkali metals by electrolysis of salt melts. Thus almost simultaneously with the creation of the first electrochemical power source - the "galvanic cell" or "galvanic battery" - many electrochemical processes were discovered and the foundations were laid of the science which to-day we call electrochemistry. 

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