An ideal gas expands isothermally at 570 K from 12 L to 36 L with 0.4 moles . What is the work done by the gas? ( R = 8.
**First law of thermodynamics** ΔU = Q - W, ΔU internal energy change (J), Q heat added to system (J), W work done by system (J), sign convention physics Q positive when added, W positive when done by system, energy conservation, for isochoric W=0 ΔU=Q, for adiabatic Q=0 ΔU=-W, for isothermal ΔU=0 Q=W, for cyclic ΔU=0 Q_net=W_net. For isothermal: W = μ R T ln((V₂)/(V₁)) . μ = 0.4 , R = 8.3 , T = 570 , V₂ = 36 , V₁ = 12 . W = 0.4 × 8.3 × 570 × ln((36)/(12)) = 1892.4 × ln(3) . ln(3) ≈ 1.0986 , W
Ref: NCERT > Physics Book > Thermodynamics > First Law of Thermodynamics Applications