Materials Science and Engineering
Physical Chemistry: Gibbs Free Energy

#4.12
"An ideal gas is allowed to expand reversibly and isothermally (25ºC) from a pressure of 1 bar to a pressure of 0.1 bar. (a) What is the change in molar Gibbs energy? (b) What would be the change in molar Gibbs energy if the process occured irreversibly?"

/\G = nRTln(P2/P1)
/\G = (1 mol) * 8.3145 J/(K mol) * (298.15 K) (ln (0.1 bar / 1 bar))
/\G = -5708 J/mol

Since Gibbs Free Energy is a state function, it is path independent and will yield the same change in Gibbs Free Energy, whether the process is reversible or not.

Materials Science and EngineeringPhysical Chemistry: Gibbs Free Energy

/\G = nRTln(P2/P1) /\G = (1 mol) * 8.3145 J/(K mol) * (298.15 K) (ln (0.1 bar / 1 bar)) /\G = -5708 J/mol

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Materials Science and Engineering
Physical Chemistry: Gibbs Free Energy

/\G = nRTln(P2/P1)
/\G = (1 mol) * 8.3145 J/(K mol) * (298.15 K) (ln (0.1 bar / 1 bar))
/\G = -5708 J/mol

Return to Physical Chemistry Page
Return to Materials Science Page
Return to Seth's Home Page