At equilibrium condition, the chemical potential of a material in different phases in contact with each other is equal. The chemical potential for a real gas (μ) is given by(where, μ = standard chemical potential at unit fugacity (f° = 1 atm.) and the gas behaves ideally.)

• A. μ° + T lnf
• B. μ° + R/T lnf
• C. μ°+ R lnf
• D. μ° + RT ln f

Answer: (D)