( 2 ) Qr = 0， T1p1(1?)/? = T2 p2(1?)/?，? = 1.4
T2 = 197 K
－
－
?U = n ?H = n
(?T) = 5 / 2×8.314×( 197－240.6 ) J = －157.966 J (?T) = 7 / 2×8.314×( 197－240.6 ) J = －221.15 J
W = ?U = －157.966 J
[8.0分]8.答案解: W = －p(外) ( Vg－Vl ) ?－nRT =－
-3
×8.314×( 273.15＋80.2 )×10 kJ =－3.76 kJ
Q = 395.0×100×10-3 kJ =39.5 kJ
?H = Q = 39.50 kJ
?U = Q＋W = [ 39.5 ＋(－3.76 )] kJ = 35.74 kJ 六、证明(1小题,共12.0分)
[12.0分]1.答案解：（1）范德华方程为： 而 故 （2）因
?H = ?U + ?( pV ) 由范德华方程得：
，积分得：