2 moles of ideal gas at 27°C temperature is expanded reversibly from 2 lit. to 20 lit. find entropy — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

The change of entropy rev q dS T From the first law of thermodynamics, Dq = dU + PdV = CvdT + PdV THERMODYNAMICS AND THERMOCHEMISTRY 37 V V V 2 2 V 1 1 dq dT P C dV T T T dq dT RdV P R C For 1 mole of a gas, T T V T V dT dV dS C T V T V S C ln R ln [for one mole of ideal gas] T V >> >> >> Hence 2 2 1 1 T T T 27 C 300K ln 0 V 2 1 V 20 S Rln 2ln 2ln10 4.605 V 2 S 4.605cal/mol K Entropy change for 2 moles of gas = 2 × 4.605 cal/K = 9.2 cal/K