过a→c Qa=vC2(271-71)=vR71=5RT=5×8.31×300 2 1.2465×10() Qab=+Qb=Qa=1.2465×10( 亦可对a→b,全过程写热力学第一定律得Qb Qb=△Eab+W ab VA VRT 解:g dv= vRT In (吸热) VRT In3=1.IvRT On =vC ( T-TH )=·R(T。-7)(放热 2 ,=0 ca为绝热过程,写绝热过程方程: y 14过 a→c 1 1 1 1 5 (2 ) 5 5 8.31 300 2 Q vC T T v RT RT ac p = − = = =   4 =  1.2465 10 ( ) J 4 1.2465 10 ( ) Q Q Q Q J ab ac cb ac = + = =  亦可对 a→b，全过程写热力学第一定律得 Qab Q E W W ab ab ab ab =  + = 5.. 解 ： ln b b a V V a b ab ab a Va V a vRT V Q W pdV dV vRT V V = = = =   (吸热) ln3 1.1 a a = = vRT vRT 5 ( ) ( ) 2 Q vC T T v R T T bc v c b c a = − =  − (放热) 0 Qca = ca 为绝热过程，写绝热过程方程： 1 1 T V T V c b a a   − − = ， ' 7 2 1.4 5 2 P V R C C R  = = =