1、Physical ChemistryUniversity of Science and Technology Beijing克劳修斯不等式克劳修斯不等式Physical ChemistryUniversity of Science and Technology Beijing克劳修斯不等式克劳修斯不等式Physical ChemistryUniversity of Science and Technology Beijing克劳修斯不等式克劳修斯不等式Physical ChemistryUniversity of Science and Technology Beijing思考：思考：Phys
2、ical ChemistryUniversity of Science and Technology Beijing熵判据熵判据Physical ChemistryUniversity of Science and Technology Beijing熵增原理熵增原理Physical ChemistryUniversity of Science and Technology Beijing用孤立体系的熵变判断自发性用孤立体系的熵变判断自发性Physical ChemistryUniversity of Science and Technology Beijing把非孤立体系的熵变判断自发性把非
3、孤立体系的熵变判断自发性体系环境孤立Physical ChemistryUniversity of Science and Technology Beijing判断依据判断依据用热力学第二定律表达式判断过程的方向用热力学第二定律表达式判断过程的方向，只能判断，只能判断可逆和不可逆可逆和不可逆；用用S0判断过程是判断过程是自发还是非自发自发还是非自发，体，体系必须是孤立体系。系必须是孤立体系。可逆or不可逆第二定律自发or非自发熵判据Physical ChemistryUniversity of Science and Technology Beijing熵变的计算熵变的计算基本上都是从定义式出
4、发；基本上都是从定义式出发；切记要用切记要用可逆过程可逆过程的热温熵来计算；的热温熵来计算；若实际过程不可逆，则利用熵变与途径无关若实际过程不可逆，则利用熵变与途径无关，在始末态间，在始末态间设计可逆途径设计可逆途径进行计算。进行计算。Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变理想气体的等温变化理想气体的等温变化Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变理想气体的等温变化理想气
5、体的等温变化Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变理想气体的等温变化理想气体的等温变化Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变理想气体的等温混合理想气体的等温混合Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变理想气体的等温混合理想气体的等温混合Physical Che
6、mistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变等温等压可逆相变等温等压可逆相变Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变等温等压可逆相变等温等压可逆相变Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变等温等压可逆相变等温等压可逆相变Physical ChemistryUniversity of Scie
7、nce and Technology Beijing等温过程的熵变等温过程的熵变等温等压可逆相变等温等压可逆相变Physical ChemistryUniversity of Science and Technology Beijing等温过程的熵变等温过程的熵变等温等压可逆相变等温等压可逆相变Physical ChemistryUniversity of Science and Technology Beijing变温过程的熵变变温过程的熵变等容变温过程和等压变温过程等容变温过程和等压变温过程Physical ChemistryUniversity of Science and Techno
8、logy Beijing理想气体的任意过程理想气体的任意过程先等温后等容先等温后等容21VTSSS12,12lnlnTTnCVVnRmV1(p1V1T1)2 (p2V2T2)pV21,1121lnTTmVTdTnCTVVnRT1(p1V2T1)Physical ChemistryUniversity of Science and Technology Beijing理想气体的任意过程理想气体的任意过程先等压后等温先等压后等温21TpSSS2112,lnlnppnRTTnCmp1(p1V1T1)2(p2V2T2)pV2122,ln21TVVnRTTdTnCTTmp1(p1V1T2)Physica
9、l ChemistryUniversity of Science and Technology Beijing理想气体的任意过程理想气体的任意过程先等压后等容先等压后等容21VpSSS12,12,lnlnppnCVVnCmVmppV1(p1V1T1)2(p2V2T2)12,11,lnlnTTnCTTnCmVmp1(p1V2T1)Physical ChemistryUniversity of Science and Technology Beijing理想气体的任意过程理想气体的任意过程作业作业2-7：三个公式互相推导：三个公式互相推导Physical ChemistryUniversity o
10、f Science and Technology Beijing两个恒温热源之间的自发热传导两个恒温热源之间的自发热传导Physical ChemistryUniversity of Science and Technology Beijing两个变温热源之间的自发热传导两个变温热源之间的自发热传导热源1热源2终态Physical ChemistryUniversity of Science and Technology Beijing环境的熵变环境的熵变Physical ChemistryUniversity of Science and Technology Beijing环境的熵变环境的
11、熵变再次考虑例题再次考虑例题4，刚才求的是体系的熵变。，刚才求的是体系的熵变。现在要求求出环境的熵变，并判断过程是现在要求求出环境的熵变，并判断过程是否是自发的，怎么办？否是自发的，怎么办？Physical ChemistryUniversity of Science and Technology Beijing环境的熵变环境的熵变Physical ChemistryUniversity of Science and Technology BeijingT-S图：热效应的直观描述图：热效应的直观描述Physical ChemistryUniversity of Science and Tech
12、nology BeijingT-S图：热效应的直观描述图：热效应的直观描述Physical ChemistryUniversity of Science and Technology BeijingT-S图：热效应的直观描述图：热效应的直观描述(1)既显示体系所作的功，又显示体系所吸取或释放的热量。p-V 图只能显示所作的功。(2)既可用于等温过程，也可用于变温过程来计算体系可逆过程的热效应；而根据热容计算热效应不适用于等温过程。Rd d QT SQC T（可用于任何可逆过程）（不能用于等温过程）Physical ChemistryUniversity of Science and Techn
13、ology Beijing作业作业2-8：绝热过程：绝热过程n=1mol单原子理想气体，始态为单原子理想气体，始态为273K、p，经绝，经绝热对抗热对抗0.5p外压膨胀至终态，试计算外压膨胀至终态，试计算S，并判断，并判断过程是否可逆。过程是否可逆。12,12lnlnSTTnCVVnRmV2112,lnlnSppnRTTnCmp12,12,lnlnSppnCVVnCmVmpPhysical ChemistryUniversity of Science and Technology Beijing作业作业2-9：绝热过程：绝热过程273K, 1 MPa, 1m3 单原子理想气体，绝热膨胀至单原子理想气体，绝热膨胀至0.1 MPa，计算，计算Q、W、U、H、S ，并判，并判断可逆性。断可逆性。（1） p外外p；（2） p外外0.1 MPa ；（3） p外外0作业作业2-10 简述克劳修斯不等式的内容与意义。简述克劳修斯不等式的内容与意义。作业作业2-11 简述简述T-S图的用途。图的用途。
