摘要
系统讨论了液、固体的Cp—Cv之值,有机液体Cp—Cv达到5R者很普通,固体的(Cp—Cv)/Cp平均也达4％,不能认为Cp—Cv≈0。产生的原因是由于液、固体恒压下体积膨胀时内位能增加较多。在实际应用中由于液体上方留有空间,固体内或固体与容器间有空隙,所以要用共存相的热容,而液、固体与气相共存时的热容与Cp相差无几,因此,即使在恒容过程中也只用Cp而不用Cv。
A systematical discussion on Cp -Cv value for liquids and solids is presented in the paper. It is general that the Cp-Cv value for organic liquids reaches up to 5R. The average value of (Cp - Cv)/Cp for solids also reaches up to 4%. Therefore Cp - Cv≈0 is not right. This is because the increase of the internal potential energy of liquids and solids is larger during the expansion at constant pressure. In practical application,the capacity of co-exist phase must be used .because there must be space above the liquids, as well as pores in the solids or gaps between solids and containers. The capacity of liquids or solids equilibrated with vapor is very close to Cp. Hence only Cp of liquids and solids instead of Cv is used even in the isochoric process.
出处
《北京石油化工学院学报》
1994年第1期1-5,共5页
Journal of Beijing Institute of Petrochemical Technology
关键词
液体
固态
热容
应用
Liquid Solid state Heat capacity Application
