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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 above equation is a modern statement of the theorem. Nernst often used a form that avoided the concept of entropy. [1] Graph of energies at low temperatures. Another way of looking at the theorem is to start with the definition of the Gibbs free energy (G), G = H - TS, where H stands for enthalpy.
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):
Variations from these ideal conditions affect measured voltage via the Nernst equation. Electrode potentials of successive elementary half-reactions cannot be directly added. However, the corresponding Gibbs free energy changes (∆G°) must satisfy ∆G° = – z FE°,
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 :
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. The expression rearranges to
The New Heat Theorem (1926). Walther Hermann Nernst ForMemRS (German pronunciation: [ˈvaltɐ ˈnɛʁnst] ⓘ; 25 June 1864 – 18 November 1941) was a German physical chemist known for his work in thermodynamics, physical chemistry, electrochemistry, and solid-state physics.
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.