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In electrochemistry, the Nernst equation is an equation that relates the reduction potential of an electrochemical reaction (half-cell or full cell reaction) to the standard electrode potential, temperature, and activities (often approximated by concentrations) of the chemical species undergoing reduction and oxidation. It is the most important equation in the field of electrochemistry. It was named after Walther Nernst, a German physical chemist who formulated the equation

$$E_{ion}$$	the equilibrium potential (Nernst potential) for a given ion	Volt
$$R$$	the universal gas constan	8.314 J.K^-1.mol^-1
$$T$$	the temperature	Kelvin
$$z$$	the valence of the ionic species. z is +1 for Na+, +1 for K+, +2 for Ca2+	Unitless
$$F$$	the Faraday's constant	96485 C.mol^-1
$$\text{Ion Out}$$	the concentration of the ionic species in the extracellular fluid	Mole
$$\text{Ion In}$$	the concentration of the ionic species in the intracellular fluid	Mole

Goldman equation is an equation used to calculate the electrical equilibium potential across the cell's membrane in the presence of more than one ions taking into account the selectivity of membrane's permeability. It is derived from the Nernst equation.

$$V_{rest}$$	the membrane potential	Volt
$$R$$	the universal gas constan	8.314 J.K^-1.mol^-1
$$T$$	the temperature	Kelvin
$$F$$	the Faraday's constant	96485 C.mol^-1
$$P_{Na}$$	the membrane permeability for Sodium	Unitless
$$P_{Cl}$$	the membrane permeability for Chlorine	Unitless
$$P_{K}$$	the membrane permeability for Potassium	Unitless
$$[Na^+]_{\text{out}}$$	the concentration of Na in the extracellular fluid	Mole
$$[Na^+]_{\text{in}}$$	the concentration of Na in the intracellular fluid	Mole
$$[Cl^-]_{\text{out}}$$	the concentration of Cl in the extracellular fluid	Mole
$$[Cl^-]_{\text{in}}$$	the concentration of Cl in the intracellular fluid	Mole
$$[K^-]_{\text{out}}$$	the concentration of K in the extracellular fluid	Mole
$$[K^-]_{\text{in}}$$	the concentration of K in the intracellular fluid	Mole

build: Apr 15, 2019

The City College of New York

This project is designed for students to better understand the Nernst and Goldman equation. More description.....

Lead by Professor Hysell Oviedo and Professor Ching-Jung Chen

Design Credit:

For questions or concerns, please contact digital@ccny.cuny.edu

$$ \small V_{rest} = \frac{RT}{F}ln \left( \frac{ P_{Na}[Na^+]_{\text{out}} + P_{Cl}[Cl^-]_{\text{in}} + P_{K}[K^-]_{\text{out}} } { P_{Na}[Na^+]_{\text{in}} + P_{Cl}[Cl^-]_{\text{out}} + P_{K}[K^-]_{\text{in}} } \right)$$