Question

Entropy change $\left(\Delta S\right)$ for the vaporization of water at ${100}^{o}C$
(Given $\Delta H_{\left(vap\right)}=40.7kJ/mol$)

• A. $40.7J/K-mol$
• B. $109.1J/K-mol$
• C. $10.91J/K-mol$
• D. $90.11J/K-mol$

Answer 1

Answer: (B)

$109.1J/K-mol$

We know that
$q=\Delta H$ at constant pressure
since, vaporization at ${100}^{o}C$ is reversible
$\therefore$ $\Delta G=0$ and
$\Delta S=\frac{q_{rev}}{T}=\frac{0.47\times {10}^3}{373.1K}=109.1J/K-mol$