Lesson eLearning

A 1 mol ideal gas expands at constant pressure from a volume of 2 L to 10 L at 300 K. Find the change in entropy (ΔS) of the gas.

medium 2 marks Class 11 · Physics · Thermodynamics
Answer
13.4 J K⁻¹

The correct answer is 13.4 J K⁻¹ — Rounded to one decimal place: 13.4 J K⁻¹

Step-by-step solution

  1. For isobaric expansion of ideal gas, ΔS = nR ln(V₂/V₁)
  2. n = 1 mol, R = 8.314 J mol⁻¹ K⁻¹
  3. V₂/V₁ = 10 L/2 L = 5
  4. ln 5 ≈ 1.6094
  5. ΔS = 8.314 × 1.6094 ≈ 13.38 J K⁻¹
  6. Rounded to one decimal place: 13.4 J K⁻¹
Common mistake: Using ΔS = Q_rev/T for non‑reversible process

Concept tested: Entropy change in isobaric expansion

Published · How this solution was prepared and checked

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