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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):
This type of cell will generate a potential that can be predicted by the Nernst equation. Both can undergo the same chemistry (although the reaction proceeds in reverse at the anode) Cu 2+ (aq) + 2 e − → Cu(s) Le Chatelier's principle indicates that the reaction is more favorable to reduction as the concentration of Cu 2+ ions increases ...
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 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.
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
This device will have an input signal, a property that we wish to quantify, and an output signal, a quantity we can register. In this case, ion selective electrode are electrochemical sensors that give potentiometric signals. The voltage is theoretically dependent on the logarithm of the ionic activity, according to the Nernst equation ...