State and explain Nernst equation.

Explanation

Nernst established a relation between the electron potential and concentration of ions in solution.
For the reaction : `M^(n+)(aq) n e^(-) to M(s)`
`E=E^(@)-(2*303RT)/(nF)"log"([M])/([M^(n+)])`
Here E is reduction potential, `E^(@)` is standard reduction potential, R is gas constant `(8.314JK^(-1)mol^(-1))`, T is temperature on Kelvin scale, F is one Faraday (96500 coulombs) and `[M^(n+)]` is molar concentration of ions in solution. since molar concentration of solids, liquid or a gas at one atmosphere is taken as unity
`therefore [M]=1`
Thus `E=E^(@)-(2*303RT)/(nF)"log"(1)/([M^(n+)])`
Substituting value of `R(8*314JK^(-1)mol^(-1)),T(298K)andF(96500)`
`E=E^(@)-(0*0591RT)/(n)"log"(1)/([M^(n+)])`
Thus reduction potential of an electrode is directly proportional the concentration of its ions in solution.