Each of the vessels 1 and 2 contain 1.2 moles of gaseous helium. The ratio of the vessels volumes is V₂/V₁ = 2.0, and the ratio of the absolute temperature of helium in them is T₁/T₂ = 2.0. Assuming t

Question

Each of the vessels 1 and 2 contain 1.2 moles of gaseous helium. The ratio of the vessels volumes is V₂/V₁ = 2.0, and the ratio of the absolute temperature of helium in them is T₁/T₂ = 2.0. Assuming the gas to be ideal, find the difference of gas entropies in these vessels, S₂ − S₁. (ln 2 = 0.7)

TestHub · Accepted Answer

S₂ − S₁ = nCᵥ,ₘ ln(T₂/T₁) + nR ln(V₂/V₁). For helium Cᵥ,ₘ = 3R/2, T₂/T₁ = 1/2, V₂/V₁ = 2. So S₂ − S₁ = 1.2 × (3R/2) × (−ln 2) + 1.2R ln 2 = 1.2R ln 2 (1 − 1.5) = −0.6 R ln 2 = −0.6 × 2 × 0.7 = −0.84 cal/K. Matches (c).

Chemistry - Thermodynamics - II Question with Solution | TestHub

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