Question:

Calculate the work done when \(1\) mole of an ideal gas is expanded reversibly and isothermally from initial pressure \(10\) bar to final pressure \(1\) bar at constant temperature \(300\) K. [\(R = 8.314\text{ J K}^{-1}\text{ mol}^{-1}\)]

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Use $w=-2.303\,nRT\log\frac{P_1}{P_2}$ for reversible isothermal expansion.
Updated On: Oct 1, 2026
  • \(-5.744\) kJ
  • \(-5.123\) kJ
  • \(-6.514\) kJ
  • \(-4.981\) kJ
Show Solution
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The Correct Option is A

Solution and Explanation

Step 1: Write the formula
For a reversible isothermal expansion, \(w=-2.303\,nRT\log_{10}\frac{V_2}{V_1}\). At constant \(T\), \(\frac{V_2}{V_1}=\frac{P_1}{P_2}\).

Step 2: Substitute
\(n=1\), \(R=8.314\), \(T=300\) K, \(\frac{P_1}{P_2}=10\), so \(\log10=1\).
\[ w=-2.303\times8.314\times300\times1=-5744\text{ J} \]

Step 3: Convert
\(w=-5.744\) kJ. The negative sign means the gas does work on the surroundings. Option (A).

Final Answer:
Work done is \(-5.744\) kJ, option (A). \[ \boxed{\text{(A) } -5.744\text{ kJ}} \]
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