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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 ...
The and pH of a solution are related by the Nernst equation as commonly represented by a Pourbaix diagram (– pH plot).For a half cell equation, conventionally written as a reduction reaction (i.e., electrons accepted by an oxidant on the left side):
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 ...
The reducing agent is stronger when it has a more negative reduction potential and weaker when it has a more positive reduction potential. The more positive the reduction potential the greater the species' affinity for electrons and tendency to be reduced (that is, to receive electrons). The following table provides the reduction potentials of ...
Since Δ r G o = -nFE o, the electrode potential is a representation of the Gibbs energy change for the given reduction. The sum of the Gibbs energy changes for subsequent reductions (e.g. from O 2 to H 2 O 2, then from H 2 O 2 to H 2 O) is the same as the Gibbs energy change for the overall reduction (i.e. from O 2 to H 2 O), in accordance ...
Unit activity for each solvent and pure solid or liquid species; and; Absolute partial pressure 101.325 kPa (1.00000 atm; 1.01325 bar) for each gaseous reagent — the convention in most literature data but not the current standard state (100 kPa). Variations from these ideal conditions affect measured voltage via the Nernst equation.
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.
The overall chemical reaction taking place in a cell is made up of two independent half-reactions, which describe chemical changes at the two electrodes. To focus on the reaction at the working electrode , the reference electrode is standardized with constant (buffered or saturated) concentrations of each participant of the redox reaction.