Standard Potential

standard potential

[′stan·dərd pə′ten·chəl]
(physical chemistry)
The potential of an electrode composed of a substance in its standard state, in equilibrium with ions in their standard states compared to a hydrogen electrode.

Potential, Standard

 

a physicochemical quantity that by convention is used to characterize the equilibrium potential difference between an electrode and a solution when the substances participating in the electrode reaction are in the standard state, that is, when the activities of the substances are equal to unity. Since there is no way to measure the actual potential difference between the electrode and the solution, quantities that characterize the potentials of different electrodes with respect to some reference electrode are used. A normal hydrogen electrode, whose potential is assumed to be zero at any temperature, is usually used as the reference electrode.

The potential of an electrode that is negatively charged with respect to the normal hydrogen electrode has a minus sign, while the potential of a positively charged electrode has a plus sign. An arrangement of the standard potentials of discharge-ionization reactions of metals and hydrogen, placed in ascending order, is called the electromotive-force series. One element will displace a second element from a solution containing the second element’s cations if the standard potential of the first element is less positive than that of the second. Standard potentials are calculated from the results of measurements of the electromotive force of voltaic cells and from the standard values of the change in the Gibbs free energy ΔG° during the reaction. The values of the standard potential can be used to calculate ΔG° and the equilibrium constant of chemical reactions. Such calculations are necessary for thermodynamic calculations and for assessing the possibility that a given chemical reaction will take place.

REFERENCES

Kireev, V. A. Kratkii kursfizicheskoi khimii. Moscow, 1963. Chapter 13, section 175.
Spravochnik khimika, vol. 3. Moscow-Leningrad, 1965.
Perel’man, V. I. Kratkii spravochnik khimika, 6th ed. Moscow, 1963. Goronovskii, I. T., Iu. P. Nazarenko, and E. F. Nekriach. Kratkii spravochnik po khimii, 3rd ed. Kiev, 1965.
References in periodicals archive ?
The electromotive force, emf, is also known as standard potential, Eo.
The thermodynamically calculated standard potential equals [E.sup.0] = 0.94 V [11].
Tenders are invited for Supply of Standard Potential Transformer
After the better resistor choice of 4.7 k[OMEGA] for R1 and 150 k[OMEGA] for R2, the steady tension 4.85 V found in the empty cell became the standard potential. The overestimated potentials were found by Nernst's equation, corroborated by Skoog et al.
Therefore there are two types of ITS standard potential system in Japan.
Importance of interfacial voltage, role of slower scan for higher flux, role of standard potential over ionic ingress and variation of process dynamics with diffusivity, standard potential are revealed for the first time for this area of research.
Although it would be easy to map them effectively within the SAP standard, this is not the common practice, which also increases the share of unused relevant standard potential to an extent that entails high financial losses for the respective company.
In anticipation of their functioning as electron-yielding electrodes, standard potential voltages have been determined for many common metals.
through the range 0[degrees] to 95[degrees] C, calculations have been made of (1) the standard potential of the silver-silver-ehloride electrode, (2) the activity eoeffieient of hydrochloric aeid in aqueous solutions from m (molality) = 0 to m=0.1 and from 0[degrees] to 90[degrees] C, (3) the relative partial molal heat content of hydrochloric acid, and (4) the relative partial molal heat capacity of hydrochloric acid.
The standard potential criteria developed by NACE International to determine whether a pipeline under cathodic protection is adequately protected is based on the idea of "close" potential.
The standard potential of this reaction is equal to 0.98 V (according to data from review [4] and handbook [16]).
of East Anglia) compile 22 articles beginning with discussion of standard potentials; formal and other characteristic potentials of selected electrode reactions; redox potential-structure relationships in coordination compounds; molecular hydrogen, hydride, and dihydrogen complexes; and redox properties and electrochemistry of oxygen.

Full browser ?