I this due to expansion volume is changed but we applied here internal energy formula which is for constant volume but here is volume is change due to expansio

Th Va}i are either T and V or T and P (i) When T & V are Two Variables according to first law of thermodynamics q= dE + W for compression (VJ) dE - W for expansion (Vt) If the work involved is due to expansion (Vt) of the aac volume dV again a Pressure P -W = P.dV = dE + P.dV So The increase in entropy of the gas for an infinitesimallv small dS= T ds dE +P.dv So T Substituting the value of dE = C.dT and PRT V we have dS-,dT I RT dS- TV T dV V dS-C R Making the assumption that Cv is independent of temperature get AS-C, In + Rin V for n moles of the ideal gases, the above equation may be AS nc, In 2 + nRIn2 T V. It is evident that the entropy change for the change of state c initial and final volumes as well as on the initial and final temperature Contact Us: Webeite www.eduncle.com Email support@eduncle.com