It turns out we can express all these functions in terms of G, G we wouldn't need to choose G, but it's a very useful function to choose.

最终我们能把所有的这些函数,用自由焓G表示出来，我们没有必要选择，但是这个选择很有用。

麻省理工公开课 - 热力学与动力学课程节选