Question

For the process, $H_2 O_{(l)} \longrightarrow H_2O_{(g)}$ at $T = 100^{\circ}\,C$ and $1$ atmosphere pressure, the correct choice is

• A. $\Delta S_{\text{system}} > 0$ and $ \Delta S_{\text{surrounding}} > 0$
• B. $\Delta S_{\text{system}} > 0 $ and $ \Delta S_{\text{surrounding}} < 0$
• C. $\Delta S_{\text{system}} < 0 $ and $ \Delta S_{\text{surrounding}} < 0$
• D. $\Delta S_{\text{system}} < 0 $ and $ \Delta S_{\text{surrounding}} > 0$

Answer 1

Answer: (B)

At $100^{\circ} C$ and $1$ atmosphere pressure
$H _{2} O (\ell) \rightleftharpoons H _{2} O ( g )$ is at equilibrium.
For equilibrium $\Delta S _{\text {total }}=0$
and $\Delta S _{\text {system }}+\Delta S _{\text {surroundirg }}=0$
$\therefore \Delta S _{\text {system }}>0$ and $\Delta S _{\text {surrounding }}<0$