Abstract: As an important physical quantity in Thermodynamics and Statistical Physics，chemical potential describes the trend of particle transition in thermodynamic systems.Here，by taking the case of“equilibrium concentration of hydrogen on tungsten surface”as an example，we introduce the concept of the chemical potential to determine equilibrium concentration.Careful analyses on the variation of the chemical potential for hdyrogen in both the molecular hydrogen system and tungsten surface system explicitly illustrate the equilibrium concentration of hydrogen on tungsten surface under different temperatures and pressures.Such equilibrium concentration calculation greatly benefits the understanding of the physical origin of chemical potential concept in Thermodynamics and Statistical Physics.

Key words: chemical potential, tungsten, hydrogen, equilibrium concentration, thermodynamic and statistical physics