Chemical potential

high-resolution terminology - matching measurements at high-resolution

Chemical potential

Description

The chemical potential of a substance B, µ_B [J/mol], is the partial derivative of Gibbs energy, G [J], per amount of B, n_B [mol], at constant temperature, pressure, and composition other than that of B,

µB = (∂G/∂nB)T,p,nj≠B

The chemical potential of a solute in solution is the sum of the standard chemical potential measured under defined standard conditions and a concentration (activity)-dependent term,

µB = µB° + RT ln(aB)

The standard state for the solute is refered to ideal behaviour at standard concentration, c° = 1 mol/L, exhibiting infinitely diluted solution behaviour.

Abbreviation: µ

Reference: Cohen 2008 IUPAC Green Book

Communicated by Gnaiger E 2018-10-18

MitoPedia concepts: Ergodynamics 

The proton chemical potential

The standard chemical potential of protons is by defintion zero. Therefore, µ_H+ depends on the activity of protons only,

µH+ = RT ln(aH+)

Since pH = -lg(a_H+), µ_H+ is related to pH as,

µH+ = -RT·ln(10)·pH

Therefore, for a difference of pH of -1 unit, Δµ_H+ equals RT·ln(10):

0 °C = 273.15 K

ln(10) = 2.302585093