Question

$3$ moles of ${CO}_2$ gas expands isothermally against external pressure of $1$ bar. Volume increases from $10L$ to $30L$ respectively. The system is in thermal contact of surroundings at temperature $15oC$. Entropy change in isothermal process is:
$\Delta S=2.303nR\log \left(\frac{V_2}{V_1}\right)$
If ${CO}_2$ behaves like an ideal gas, then entropy change of system ($\Delta S_{system}$) will be:

• A. $+27.4J{K}^{-1}$
• B. $9.1J{K}^{-1}$
• C. $-274J{K}^{-1}$
• D. $-9.1J{K}^{-1}$

Answer 1

Answer: (A)

$+27.4J{K}^{-1}$

We have,

$\Delta S=2.303\ast n\ast R\ast log\frac{V_2}{V_1}$

$\Delta S=2.303\ast 3\ast 8.314\ast log\frac{30}{10}$

$\Delta S=27.4J{K}^{-1}$