·(③)先由理想气体绝热可逆过程方程式求T2: PIYTIY=P2IYT2Y y=5/3=1.667 ● (Tz/T)1.667=(P1/p2)0.67=10-0.667=0.2153 ● T2/T=0.398 T2=119.4K ● △S=0 Q=0 (绝热可逆过程) ● W=△U=Cv(T2-T) =3/2R(119.4-300) =-2252.3J △U=一2252.3J/mol • (3) 先由理想气体绝热可逆过程方程式求T2 : • p1 1-T1 = p2 1-T2  =5/3=1.667 • (T2 /T1 ) 1.667=(p1 /p2 ) -0.667=10-0.667=0.2153 • T2 /T1=0.398 T2=119.4 K • S=0 Q=0 (绝热可逆过程) • W=U=CV(T2－T1 ) =3/2R(119.4 － 300) =-2252.3 J • U=－2252.3 J/mol