The calculation of chemical thermodynamics function is both the key point and a difficult problem in the study of physical chemistry.

化学热力学函数的计算是学习物理化学的重点和难点。

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If you have a quantity which is constant over any closed path, that quantity is a thermodynamics state function.

如果有一个物理量,对任何闭合回路积分是常数，这个物理量就是一个热力学态函数。

麻省理工公开课 - 热力学与动力学课程节选