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The work done during reversible isothermal expansion of one mole of hydrogen gas at \(25^\circ C\) from pressure of 20 a…

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The work done during reversible isothermal expansion of one mole of hydrogen gas at \(25^\circ C\) from pressure of 20 atmosphere to 10 atmosphere is:
(Given \(\mathrm{R}=2.0\mathrm{cal}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}\))

[NEET 2024]

a

100 calories

b

0 calorie

c

- 413.14 calories

d

413.14 calories

✓ Correct answer: c)

- 413.14 calories

Explanation

For isothermal reversible expansion:

\(W=−nRT\ln ⁡(\frac{{P}_{1}}{{P}_{2}})\)

\(W=−1\times 2\times 298\times \ln ⁡(\frac{20}{10})=−596\times \ln ⁡(2)\\ =−596\times (0.693)=–413.14\text{ }\text{cal}\)

OR

\(W=−2.303n\text{ }RT\text{ log}\left(\frac{{P}_{1}}{{P}_{2}}\right)\)

\(=−2.303\times 1\times 2\times 298\times \text{log}\frac{20}{10}\)

\(=−2.303\times 596\times \text{log}2\)

\(=−2.303\times 596\times 0.3010\)

\(W=−413.14\text{ calories }\)

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