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

It's a state function, so we're at constant temperature and pressure, and now we want to consider some chemical change or a phase transition or you name it.

这就是态函数，我们处于恒定的温度和压强之下，然后考虑某些化学变化或者相变,或者你想考虑的东西。

麻省理工公开课 - 热力学与动力学课程节选

And when we make these comparisons, one thing I want to point out is that we need to keep the constant principle quantum number constant, so we're talking about a certain state, so we could talk about the n equals 2 state, or the n equals 3 state.

当我们做这些比较时，我想指出的一件事是,我们需要保持常量原则,保持量子数是常数，所以我们在讨论一个确定的态时，我们可以谈论n等于2的态，或者n等于3的态。

麻省理工公开课 - 化学原理课程节选