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A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 \mathrm{~g} . When it is subjected to cooking at 100^{\circ} \mathrm{C} \text {, } then the internal energy for vaporization in \mathrm{kJ} \mathrm{mol}^{-1} is _________. [nearest integer]

[Assume steam to be an ideal gas. Given \Delta_{\text {vap }} \mathrm{H}^{\Theta} for water at 373 \mathrm{~K} and 1 bar is \left.41.1 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \mathrm{R}=8.31 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right]

Option: 1

38


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

\begin{aligned} \\&\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \\ \\&\mathrm{\Delta H=\Delta U+(\Delta n)_g R T }\\ \\&\mathrm{\Rightarrow \Delta U=\Delta H-(\Delta n)_g R T}, \mathrm{(\Delta n_g=1)} \end{aligned}

                \begin{aligned} =& \left (41.1-\frac{1 \times 8.31 \times 373}{1000} \right ) \mathrm{~kJmol^{-1}} \\ =& \left (41.1-3.1 \right ) \mathrm{~kJmol^{-1}} \\ =& 38 \mathrm{~kJmol^{-1}} \end{aligned}

Hence, the answer is 38.

Posted by

Ajit Kumar Dubey

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