It is used when studying cell membranes in an equation similar to Fick's law.
This equation can be used to map out a Pourbaix and Frost diagram.  It is used when studying cell membranes in an equation similar to Fick's law. Since one term in it is equal to zero at equilibrium, it is often used to calculate the equilibrium constant and it can be derived using a formula equal to the negative change in Gibbs Free Energy. It explains why certain net reactions can occur in a concentration cell, and it is the basic principle behind pH electrodes.  At 25 degrees Celsius, it includes a term equal to about .059; this term includes the Faraday constant. FTP, identify this equation in electrochemistry that allows for the calculation of the potential for a galvanic cell. 
This equation can be used to map out a Pourbaix and Frost diagram.  
{Nernst} equation