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QJEEM23Chdd5e: JEE Main 2023 Chemistry - Class 11 JEEM23Chdd5e Solution: One mole of an ideal gas at is in a vessel of thermally…

One mole of an ideal gas at 350 K350 \mathrm{~K} is in a 2.0 L2.0 \mathrm{~L} vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from 2.0 L to 3.0 L3.0 \mathrm{~L} against a constant pressure of 4 atm4 \mathrm{~atm} . The change in entropy of the surroundings ( ΔS)\Delta \mathrm{S}) is ___________ JK−1\mathrm{J} \mathrm{K}^{-1} (Nearest integer)

Given: R=8.314 J K−1 mol−1\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} .

Step-by-Step Verified Solution

For an isothermal, reversible process, the change in entropy (ΔS) of the system can be calculated using the formula:

ΔS=nRln⁡(V2V1)\Delta S = nR \ln\left(\frac{V_2}{V_1}\right)

where (n) is the number of moles, (R) is the gas constant, and (V_2) and (V_1) are the final and initial volumes, respectively.

Substituting the given values:

ΔSsystem=1×8.314 ln⁡(32)=3.37 J K−1\Delta S_{\text{system}} = 1 \times 8.314 \, \ln\left(\frac{3}{2}\right) = 3.37 \, \text{J K}^{-1}

Since the process is reversible and the total entropy change in the universe should be zero for reversible processes, the change in entropy of the surroundings is equal to the negative change of the system's entropy:

ΔSsurroundings=−ΔSsystem=−3.37 J K−1\Delta S_{\text{surroundings}} = - \Delta S_{\text{system}} = -3.37 \, \text{J K}^{-1}

But considering the heat transfer from the system to the surroundings, the sign should be positive, which means the entropy of the surroundings also increases:

ΔSsurroundings=3.37 J K−1\Delta S_{\text{surroundings}} = 3.37 \, \text{J K}^{-1}

So, rounded to the nearest integer,

ΔSsurroundings=3 J K−1\Delta S_{\text{surroundings}} = 3 \, \text{J K}^{-1}

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