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This equation is the equation of a straight line for as a function of pH with a slope of () volt (pH has no units). This equation predicts lower E h {\displaystyle E_{h}} at higher pH values. This is observed for the reduction of O 2 into H 2 O, or OH − , and for reduction of H + into H 2 .
In aqueous solutions, redox potential is a measure of the tendency of the solution to either gain or lose electrons in a reaction. A solution with a higher (more positive) reduction potential than some other molecule will have a tendency to gain electrons from this molecule (i.e. to be reduced by oxidizing this other molecule) and a solution with a lower (more negative) reduction potential ...
In electrochemistry, the Nernst equation is a chemical thermodynamical relationship that permits the calculation of the reduction potential of a reaction (half-cell or full cell reaction) from the standard electrode potential, absolute temperature, the number of electrons involved in the redox reaction, and activities (often approximated by concentrations) of the chemical species undergoing ...
During the early development of electrochemistry, researchers used the normal hydrogen electrode as their standard for zero potential. This was convenient because it could actually be constructed by "[immersing] a platinum electrode into a solution of 1 N strong acid and [bubbling] hydrogen gas through the solution at about 1 atm pressure".
A redox indicator (also called an oxidation-reduction indicator) is an indicator which undergoes a definite color change at a specific electrode potential. The requirement for fast and reversible color change means that the oxidation-reduction equilibrium for an indicator redox system needs to be established very quickly. Therefore, only a few ...
Both the oxidation and reduction steps are pH dependent. Figure 1 shows the standard potentials at pH 0 (strongly acidic) as referenced to the normal hydrogen electrode (NHE). 2 half reactions (at pH = 0) Oxidation 2H 2 O → 4H + + 4e − + O 2 E° = +1.23 V vs. NHE Reduction 4H + + 4e − → 2H 2 E° = 0.00 V vs. NHE
Examples of substances that are common reducing agents include hydrogen, carbon monoxide, the alkali metals, formic acid, [1] oxalic acid, [2] and sulfite compounds. In their pre-reaction states, reducers have extra electrons (that is, they are by themselves reduced) and oxidizers lack electrons (that is, they are by themselves oxidized).
Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H –pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system.