So for the reversible process, the work done is the integral under the pressure volume state function, the function of state.

对可逆过程，做的功,是压强体积态函数曲线下，的积分面积。

麻省理工公开课 - 热力学与动力学课程节选

It tells you what kind of molecule it is andgives you twovariables that are state variables You could have the volume and the temperature.

告诉你它是哪种分子,还给你了两个状态变量,它们可以是体积或温度。

麻省理工公开课 - 热力学与动力学课程节选

And the equation of state, pressure versus volume at constant temperature, is going to have some form, let's just draw it in there like that.

系统的态函数，恒温下压强比体积，变化曲线，就像这样。

麻省理工公开课 - 热力学与动力学课程节选

But now, what happens if, instead we look at what happens when we go to some state one to some other state two and it's the pressure. Or the volume, that changes.

但是现在，我们看看如果,我们关系从状态一变化到状态二时,体积或者压强发生变化。

麻省理工公开课 - 热力学与动力学课程节选

You know how pressure changes with temperature at constant volume if you know the equation of state.

如果你知道状态方程,知道在体积恒定的时压强如何随着温度变化。

麻省理工公开课 - 热力学与动力学课程节选

So now, this equation here relates three state functions together: the pressure the volume, and the temperature. Now, if you remember, we said that if you had a substance, if you knew the number of moles and two properties, you knew everything about the gas.

压强，体积和温度,大家应该还记得,我们提过，只要知道气体的摩尔数,和任意两个状态函数,就可以推导出其他的状态函数，这样，我们可以把它改写成。

麻省理工公开课 - 热力学与动力学课程节选

But because in many cases we can reasonably either model or measure equations of state, collect data for a material for its temperature, pressure, volume relations, then in fact if we can relate all these quantities to those then in fact we really can calculate essentially all of the thermodynamics. For the material.

但是因为在很多情况下,我们能够合理的给出状态方程的模型,或者通过收集一个物质的，温度，压强和体积之间的关系,来测量其状态方程，所以实际上我们可以给出压强等物理量,和热力学势之间的关系,并计算出所有的热力学势，对于给定的物质。

麻省理工公开课 - 热力学与动力学课程节选