2nd law direction of change Hist doesn't flow spontaneously from cool to hot body. Stol 70 Stol Ss ys + Sum A spontaneous process points towards direction in which total entropy increases. S is a state function f as = dqrev , DS = dqrew T T DS for system of isothermal expansion of perfect gas. DU20; qp-w; arev 2 -When When -nRTln vf/vi arev nRTln vt/vi ds= darwf & DS2 nRln vthi or DSm' nRenvitivi DS for apertect gas.
W20, DU=0 -) q 0 no heat abs or removed DSm' Ren Vf/vi DStatal 2 Rln vf/vi VI 7Vi, spontaneous (irr) iso exp if gas is accompanied by increase in entropy. Iso Rev Exp W2 -PDV cy qrev' PDV Stotal 2 Dsys DSsurr gnev + -anev 20 T T Clausius Ineq dsz dq TT In isolated, dq 20 dszo Rev process. d State = 0 spontaneous in neither direction Cy is at eq Irr. d Stotal 7 d Ssyst disurr 70 All spontaneous process occurring in nature are irreversible by entropy of universe is increasing continuously Energy of universe remains constant; entropy of Ist cy2nd Law summed : universe tends Howards max: strange in entropy
DS idealgas 1mol with variable Two DS, Culn If + Rln VI Ti Vi variable PCT DS2 Cpln Tf- R n Pf Ti Pi IG in isot process DST 2 RCn Vf 2 Rhn Pf Vi Pi I9 in irobanic PSp 2 cpln FH/T Isochonic DSv Cven If Ti Heat Engine Device that transforms heat into work Happens in cyclin process Req. Grot resenvir to supply energy (QH) cyclel reservoir to take in excess energy(Qc) 4H70 Cy Qc LO