Question

Oxygen gas weighing $64g$ is expanded from $1atm$ to $0.1atm$ at $30{}^{o}C.$ Calculate entropy change, assuming the gas to be ideal

• A. $34.29J{K}^{-1}$
• B. $38.29J{K}^{-1}$
• C. $44.29J{K}^{-1}$
• D. $48.29J{K}^{-1}$

Answer 1

The correct option is B $38.29J{K}^{-1}$

The number of moles of Oxygen gas weighing 64 g can be calculated as follows
$n=\frac{Givenweight}{Molarweight}=\frac{64}{32}=2$

The expression for the change in entropy for an isothermal process is given by
$△S=2.303nRlog\left(\frac{P_1}{P_2}\right)$
$=2.303\times 2\times 8.314log\left(\frac{1}{0.10}\right)$
$=38.29J{K}^{-1}$