Question

What entropy change is involved in the isothermal expansion of $5\, mol$ of ideal gas from a volume of $10\, L$ to $100\, L$ at $300\, K$?

• A. $-95.7 \,J K ^{-1}$
• B. $+95.7 \,J K ^{-1}$
• C. $28.72\,kJ \,K ^{-1}$
• D. $-28.72\, kJ\, K ^{-1}$

Answer 1

Answer: (B)

$\Delta S=n R \ln \frac{V_{2}}{V_{1}}=2.303 n R \log \frac{V_{2}}{V_{1}}$

$=2.303 \times 5 mol \times\left(8.314 JK ^{-1} mol ^{-1}\right) \log \frac{100 L }{10 L }=95.7 JK ^{-1}$