Question

Two moles of an ideal gas are compressed isothermally $\left({100}^{o}C\right)$ and reversibly from a pressure of 10 atm to 25 atm. The value of Gibb's free energy change is:

• A. -3.684 kJ
• B. +5.684 kJ
• C. +3.684 kJ
• D. -5.684 kJ

Answer 1

Answer: (B)

+5.684 kJ

For isothermal reversible process:
$W_{rev}=-2.303nRT\log \left(\frac{P_1}{P_2}\right)$
$=-2.303\times 2\times 8.314\times 373\times \log \left(\frac{10}{25}\right)$$=+5684.1J$
$W_{rev}=+5.684kJ$
Since, $W_{rev}$ is a measure of free energy,
i.e., $\Delta G=W_{rev}=W_{max}$
$\therefore \Delta G=+5.684kJ$