Question

The enthalpy change for the transition of liquid water to steam is $40.8\mathrm{kJ}\mathrm{mol}^{-1}$ at 373 K. Calculate the entropy of vaporisation of water.

• A. $109.4\mathrm{JK}^{-1}\mathrm{mol}^{-1}$
• B. $10.94\mathrm{JK}^{-1}\mathrm{mol}^{-1}$
• C. $1.094\mathrm{JK}^{-1}\mathrm{mol}^{-1}$
• D. $1009.4\mathrm{JK}^{-1}\mathrm{mol}^{-1}$

Hint:

$\Delta S_{vap} = \frac{\Delta H_{vap}}{T_{bp}}$.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
$\Delta S_{vap} = \frac{\Delta H_{vap}}{T_{bp}}$.
Step 2: Detailed Explanation:
$\Delta S_{vap} = \frac{40.8 \times 10^3}{373} = 109.4$ J K$^{-1}$ mol$^{-1}$.
Step 3: Final Answer:
Entropy of vaporisation is $109.4$ J K$^{-1}$ mol$^{-1}$.