Question

What will be the entropy change of the system when expansion of 1 mole of a gas takes place from 3 L to 6 L under isothermal conditions? Consider, $R=2\text{ cal }\text{K}^{- 1}mol^{- 1}$ and $log 2=0.301.$

• A. $2.84\text{ cal }\text{K}^{- 1}$
• B. $1.386\text{ cal }\text{K}^{- 1}$
• C. $0.37\text{ cal }\text{K}^{- 1}$
• D. $5.26\text{ cal }\text{K}^{- 1}$

Answer 1

Answer: (B)

$n=1,V_{i}=3L,V_{f}=6L$

$\Delta S=2.303nRlog_{10} \frac{V_{f}}{V_{i}}$

$\Delta S=2.303\times 1\times 2log \frac{6}{3}=2.303\times 2\times 0.3010$

$=1.386\text{ cal }\text{K}^{- 1}$