Calculate the entropy change (Δ S) when 1 mol of an ideal gas is compressed isothermally from 20 L to 5 L at 400 K. (R =
Δ S = nR ln(V₂/V₁) = 1 × 8.314 × ln(5/20) = 8.314 × ln(0.25) = 8.314 × (-1.386) = -11.52 J/K.
Ref: NCERT Class 11 Chemistry > Chapter 5: Thermodynamics > Topic: Bond Enthalpy and Entropy and Spontaneity