Question

The enthalpy of vaporization of water at ${100}^{\circ }\text{C}$ is $40.63{\text{kJ mol}}^{-1}$. Its entropy of vaporization would be:

• A. $406.3{\text{J K}}^{-1}{\text{mol}}^{-1}$
• B. $108.9{\text{J K}}^{-1}{\text{mol}}^{-1}$
• C. $606.3{\text{J K}}^{-1}{\text{mol}}^{-1}$
• D. $4063\text{kJ}{\text{mol}}^{-1}$

Answer 1

The correct option is B $108.9{\text{J K}}^{-1}{\text{mol}}^{-1}$

$\Delta S=\frac{\Delta H}{T}$
$\Rightarrow \Delta S=\frac{40.63\times {10}^3{\text{J mol}}^{-1}}{373\text{K}}=108.9{\text{J K}}^{-1}{\text{mol}}^{-1}$
Hence, the correct answer is option (b).