Question

The accompanying diagram represents a reversible carnot cycle for an ideal gas

What is the Gibbs free energy charge during the process A→BA→B?

• A. 150 kJ
• B. -150 kJ
• C. 30 kJ
• D. can not calculate as data are not sufficient

Answer 1

Answer: (B)

-150 kJ

Gibbs free energy $\Delta G=\Delta H-T\Delta S$

Since process A-B is isothermal,

$\Delta H=C_p\Delta T=0$

$\Delta S=\frac{q_{rev}}{T}=\frac{150\times {10}^3}{1000}=150J$

Therefore, $\Delta G=0-(1000\times 150)=-150kJ$

Hence, Option B is correct.