Question

For the process, $H_2{O}_{(l)}⟶H_2{O}_{(g)}$ 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 $\Delta S_{\text{surrounding }}<0$