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Chemistry · THERMODYNAMICS
हिन्दीAt 298 K, 18 g of liquid water evaporates into steam. Given \( \Delta_{\text{vap}}H^\ominus = 44.01\text{ kJ mol}^{-1} \) and \( R = 8.314\text{ J K}^{-1}\text{mol}^{-1} \), the internal energy of vaporisation (\( \Delta_{\text{vap}}U^\ominus \)) is approximately:
Correct answer · Option 3
\( 41.53\text{ kJ} \)
Explanation
For \( \text{H}_2\text{O}(l) \to \text{H}_2\text{O}(g) \), \( \Delta n_g = 1 \). \( \Delta_{\text{vap}}U^\ominus = \Delta_{\text{vap}}H^\ominus - \Delta n_g RT = 44.01\text{ kJ} - (1 \times 8.314 \times 10^{-3} \times 298)\text{ kJ} = 44.01 - 2.48 = 41.53\text{ kJ} \).
