Plz explain the encircled part .. l expansion, expressions for two cases of e

win equations (13), (18) and (19), 1ndian b)Irreversible Adiabatic Expansion. AS n the case of irreversible isothermal expansion, expressions for Two cases of expansion are derived below: ) For free expansion. Here, Popp0 dw=-PoDn dV= 0 But dU= öw Refer to Eqn. (1)} dU=0 Further for an ideal gas, Uis a function of temperature and as dU= 0, this means that temperature of the gas remains constant after expansion, i.e., dT= 0 dH= d (U+ P) = dU+ d(PV) dU+ d(RT) = dU-+RdT= 0 +0 =0 Fora fiite change, the expressions forw, AUand AH will be W 0, AU =0, AT=0, AH=0 .20) These expressions are same as for isothermal free expansion. Hence, we conclude thatfor free expansion, uions are identical.