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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 Nernst–Planck equation is a conservation of mass equation used to describe the motion of a charged chemical species in a fluid medium. It extends Fick's law of diffusion for the case where the diffusing particles are also moved with respect to the fluid by electrostatic forces. [1] [2] It is named after Walther Nernst and Max Planck.
Concentration of X in solvent A/concentration of X in solvent B=Kď If C 1 denotes the concentration of solute X in solvent A & C 2 denotes the concentration of solute X in solvent B; Nernst's distribution law can be expressed as C 1 /C 2 = K d. This law is only valid if the solute is in the same molecular form in both the solvents.
One can calculate the potential developed by such a cell using the Nernst equation. [1] A concentration cell produces a small voltage as it attempts to reach chemical equilibrium , which occurs when the concentration of reactant in both half-cells are equal.
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):
The Gran plot is based on the Nernst equation which can be written as = + {+} where E is a measured electrode potential, E 0 is a standard electrode potential, s is the slope, ideally equal to RT/nF, and {H +} is the activity of the hydrogen ion.
For a cell reaction characterized by the chemical equation: O x + n e − ↔ R e d {\displaystyle Ox+ne^{-}\leftrightarrow Red} at constant temperature and pressure, the thermodynamic voltage (minimum voltage required to drive the reaction) is given by the Nernst equation :
ions as Ag metal onto the surface of the Ag wire). The reaction has been proven to obey these equations in solutions of pH values between 0 and 13.5. The Nernst equation below shows the dependence of the potential of the silver-silver(I) chloride electrode on the activity or effective concentration of chloride-ions: