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For example, from Fe 2+ + 2 e − ⇌ Fe(s) (–0.44 V), the energy to form one neutral atom of Fe(s) from one Fe 2+ ion and two electrons is 2 × 0.44 eV = 0.88 eV, or 84 907 J/(mol e −). That value is also the standard formation energy (∆ G f °) for an Fe 2+ ion, since e − and Fe( s ) both have zero formation energy.
Bipolar electrochemistry scheme. In electrochemistry, standard electrode potential, or , is a measure of the reducing power of any element or compound.The IUPAC "Gold Book" defines it as; "the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode".
To avoid possible ambiguities, the electrode potential thus defined can also be referred to as Gibbs–Stockholm electrode potential. In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of E for a half-cell reaction when it is written as a reduction.
The difference can be measured as a difference in voltage potential: the less noble metal is the one with a lower (that is, more negative) electrode potential than the nobler one, and will function as the anode (electron or anion attractor) within the electrolyte device functioning as described above (a galvanic cell).
For example, for oxygen, the species would be in the order O 2 (0), H 2 O 2 (–1), H 2 O (-2): The arrow between O 2 and H 2 O 2 has a value +0.68 V over it, it indicates that the standard electrode potential for the reaction: O 2 (g) + 2 H + + 2 e − ⇄ H 2 O 2 (aq) is 0.68 volts.
A different definition for the absolute electrode potential (also known as absolute half-cell potential and single electrode potential) has also been discussed in the literature. [3] In this approach, one first defines an isothermal absolute single-electrode process (or absolute half-cell process.) For example, in the case of a generic metal ...
The potential of zero charge is used for determination of the absolute electrode potential in a given electrolyte. IUPAC also defines the potential difference with respect to the potential of zero charge as: E pzc = E − E σ=0. where: E pzc is the electrode potential difference with respect to the point of zero charge, E σ=0; E is the ...
From Wikipedia, the free encyclopedia. Redirect page. Redirect to: Standard electrode potential (data page)