思考题和习题解答 8.1mol0℃、02MPa的理想气体沿着p/=常数的可逆途径到 达压力为04MPa的终态。已知Cm=(5/2)R,求过程的Q、W、△U △H、△S 解: nRT(1×83145×27315 0.2×10 13=B=点 P1102×113dm3=2270dm3 7=22「040)(270×0)K=1092K 1×8.3145 (P2 v2-P,V) (0×2270-02×1135)×10 M=m283502 =1702×103J=1702kJ 3145×(092-273) 2383×10J=23.83kJ Q=△U-W=[1702-(-3405)k=2043kJ·52· 思考题和习题解答 Q = 0 W U = = Δ 5566 J 0 d R Δ = = ∫ − T Q S 18. 1 mol 0℃、0 2. MPa 的理想气体沿着 p /V = 常数的可逆途径到 达压力为0 4. MPa 的终态。已知CV (5/ 2)R o ,m = ，求过程的Q、W 、ΔU 、 ΔH 、ΔS 。 解： 3 3 3 3 6 1 1 1 = 11.35 10 m = 11.35 dm m 0.2 10 1 8.3145 273.15 − × ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ × × × = = p nRT V p V p V 2 2 1 1 = ∴ V p p 2 V2 1 1 0 4 0 2 = =× = 1135 22 70 . . . . dm dm 3 3 ( ) ( ) K = 1092 K 1 8.3145 0.4 10 22.70 10 6 3 2 2 2 ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ × × × × = = − nR p V T ( ) ( ) ( ) = 3.405 kJ 0.4 22.70 0.2 11.35 10 J 2 1 2 1 2 1 d d 3 2 2 1 1 2 1 2 2 1 1 1 1 2 1 2 1 − ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ = − × × − × × = − − = − ⋅ − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ = − = − ∫ ∫ p V p V V V V p V V V p W p V V V V V ( ) =17.02 10 J =17.02 kJ 8.3145 1092 273 J 2 5 1 3 o ,m × ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ΔU = nCV ΔT = × × × − 8.3145 ( ) 1092 273 J 2 7 1 o ,m ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ΔH = nCp ΔT = × × × − = 23.83 10 J = 23.83 kJ 3 × Q = ΔU −W = [ ] 17.02 − ( ) − 3.405 kJ = 20.43 kJ