Question

Calculate the change in the molar Gibbs energy of hydrogen gas when its pressure is increased isothermally from 1.0 atm to 100.0 atm at 298 K.

Answer 1

Given that; pressure is increased isothermally from 1.0 atm to 100.0 atm at 298 K. thus dT = 0

To calculate the change in the molar Gibbs energy of hydrogen gas when its pressure is increased isothermally we use following experssion

dG = VdP - SdT

here the process is isothermal pressure change:

dG = VdP


ΔG = V*ΔP

ΔG = V*(100.0 atm -1.0 atm) = V*( 99.0 atm)

The molar volume of hydrogen gas at 298 K = 22.4 L / Mole

Therefore;                                            

ΔG = 22.4 L/ mole*( 99.0 atm)

= 2217.6 atm *L / mole

We know that;

1 (atm * L) / mole = 101.32500 J / mole

Then;

2217.6 atm *L / mole

= 224 698.32 J / mole

Or

224 .69832K J / mole