关于《物理化学》教材中一道习题的讨论

Discussion on a Question of Physical Chemistry Teaching Material

对《物理化学》教材中一道关于熵变计算的习题进行了讨论,指出求系统熵变时,要先根据所研究的系统条件进行分析,因为条件不同(绝热恒容和绝热恒压),所应用的公式也不同(ΔU=ΔU(A)+ΔU(B)=0,ΔH=ΔH(A)+ΔH(B)=0)。由此提出在利用物理化学公式时,必须正确理解每个公式的适用条件和范围,否则就会走进误区,不能得到正确的结论。

The paper discusses an exercise about entropy change in Physical Chemistry.When entropy change is demanded,we should analyze it according to the system condition studied.If the conditions are different（thermal insulation and constant volume,thermal insulation and constant voltage）,the formulas used are different（ΔU=ΔU（A）＋ΔU（B）=0,ΔH=ΔH（A）＋ΔH（B）=0）.So it is preferable that you must understand the condition of application and scope of every formula as you use physical chemistry formula,or you will go into the wrong area so that you can＇t get the right conclusion.