Question

Predict the sign of $\Delta S$ for each of the following processes, which occur at constant temperature:
$I$. The volume of $2$ mol of $O_2\left(g\right)$ increases from $44L$ to $54L$
$II$. The pressure of $2$ mil of $O_2\left(g\right)$ increases from $1$ atm to $1.2$ atm.

• A. $\left(I\right)\to \Delta S=-ve$; $\left(II\right)\to \Delta S=-ve$
• B. $\left(I\right)\to \Delta S=-ve$; $\left(II\right)\to \Delta S=+ve$
• C. $\left(I\right)\to \Delta S=+ve$; $\left(II\right)\to \Delta S=-ve$
• D. $\left(I\right)\to \Delta S=+ve$; $\left(II\right)\to \Delta S=+ve$

Answer 1

The correct option is C $\left(I\right)\to \Delta S=+ve$; $\left(II\right)\to \Delta S=-ve$

I. On increasing the volume from $44Lto54L$ the degree of randomization increases and hence, entropy also increases,

so we get $\Delta S=+ve$

II. The entropy of the system decreases on increasing the pressure, so we get

$\Delta S=-ve$