Question

The fugacity coefficient of a certain gas at 290K and 3.1MPA is .70. Calculate the difference of its molar Gibbs energy from that of a perfect gas in the same state.

Answer 1

Given: Temperature, T=290 K

Pressure, P= 3.1 MPa

Fugacity Coefficient of gas, =0.70

For an ideal gas, molar Gibbs Energy is given as

For an ideal gas, G_m=G⁰_m

where G_m is Molar Gibbs Energy

G⁰_m Standard Molar Gibbs Energy

R is Universal Gas Constant, R=8.314 J/mol K

T is the Temperature

p and p⁰ is the Pressure of Gas

For a real gas, the molar Gibbs energy is

where f is the Fugacity of gas

Subtract Equation 2 and Equation 1,

Fugacity coefficient is

Substitute the values

the difference of Molar Gibbs Energy of a Gas and that of an Ideal Gas is G_m-G⁰_m= -0.86 kJ/mol