All right, so this is the heat flowing in or out of the system, and these are all functions of state.

好的，这就是系统的热量变化,这些都是态函数。

麻省理工公开课 - 热力学与动力学课程节选

So that's our work in this path and heat.

这就是这个过程中的功和热。

麻省理工公开课 - 热力学与动力学课程节选

This one turns out to be the heat capacity, and this one turns out to be something that we measure in the Joule-free expansion.

其实，这就是热容，这是焦耳自由膨胀实验中,我们要测量的物理量。

麻省理工公开课 - 热力学与动力学课程节选

Heat capacity relates the amount of heat that you add to the system to the change in temperature, and this is the relationship.

热容联系起给系统提供的,热量和温度的变化，关系式是这样的：

麻省理工公开课 - 热力学与动力学课程节选

But that's an empirical observation, that heat flows in this direction.

但是我们只是根据，经验观察。

麻省理工公开课 - 热力学与动力学课程节选

q2 So q2, the heat in this way is negative.

所以沿这个方向的，是负的。

麻省理工公开课 - 热力学与动力学课程节选

So in this case here, I cool and then I heat.

因此我们这个路径中。

麻省理工公开课 - 热力学与动力学课程节选

In this case here, I heat and then I cool.

需要先冷却再加热。

麻省理工公开课 - 热力学与动力学课程节选

And if I do that then I can find out the change in enthalpy of this reaction. It's just going to be the heat of formation of these three moles of water, minus the heat of formation of the iron oxide. OK.

我就能得到这个,反应的焓的变化,它就是三摩尔水,的生成热，减去氧化铁的,生成热，好。

麻省理工公开课 - 热力学与动力学课程节选

So we'd really like to be able to find some sort of equation of state, or some sort of rather function of state that's going to relate the heat going in or out of the system with that function of state, because this isn't going to do it.

所以我们真的想要去,找到一些态方程或者态函数,通过这个态函数可以表示热量,在系统与外界的交换,因为这个不能表示它。

麻省理工公开课 - 热力学与动力学课程节选