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Path number 2 on my diagram it's a reversible, this path number 2, it's a reversible constant pressure path.
路径，首先是一个，等压过程。
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We're not going to have the constant pressure heat capacity, we're going to have the constant volume heat capacity, right.
这里出现的,不是等压热容,而是等体热容。
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Because we did work at constant pressure, and so it's just volume difference times pressure.
因为是在恒压下做功，所以功就等于体积变化乘以压力。
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This is just an equality. I have a constant pressure dH process. This term here is equal to zero.
这是一个等式，这是个恒压过程,这项等于零，这意味着。
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And so, again, we see a temperature increase, and we know the work, and the temperature increase, it's a constant pressure thing.
好，我们看到温度升高了，然后我们有做功量和温度的升高量，这是一个恒定压力下的值。
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So, these two are equal to each other as well which tells me that this derivative, Cp dH/dT constant pressure is Cp.
所以这两者也相等,这告诉我们在恒压下微分，等于。
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It's constant pressure. OK, so now, last time you looked at the Joule expansion to teach you how to relate derivatives like du/dV.
这是恒压的，好，上节课你们,学习了焦耳定律,以及怎样进行导数间的变换。
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It is taking place inside this thing, and it's a constant pressure, and we'll do it reversibly, right. So that's what we've got.
它是绝热的，在这个内反应,是在恒压下，它是可逆的，对吧？
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OK, so this, what I've sketched here would be a constant pressure calorimeter. There's a reaction.
好，我画的就是一个恒压量热计,其中进行一个反应。
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And our heat of reaction or enthalpy of reaction is defined as the enthalpy at constant pressure.
我们的反应热，或反映,的焓被定义为恒压，等温。
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Yes, exactly, it's adiabatic, right constant pressure.
对，没错，它是绝热的。
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So this is a constant pressure calorimeter.
它做了很好的隔热处理。
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You just change volume to pressure and basically you're looking at enthalpy under a constant -- anything that's done at a constant volume path with energy, there's the same thing happening under constant pressure path for enthalpy.
可以看到这就是把体积换成了压强,一般我们都是在一种恒定状态下,考虑焓的，任何在恒容条件下,能伴随能量变化的东西，也在恒压条件下伴随焓同样地变化,所以你可以经常。
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It's not constant pressure, because we have a delta p going on. It's not constant volume either.
也不是恒容，这个限制,是这个实验的限制。
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That is, it's easy to write down straight away that dG with respect to temperature at constant pressure S is minus S.
这就是说，可以很简单的写出dG在,恒定压强下对温度的偏导数,是负。
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We know how the volume and temperature vary with respect to each other at constant pressure.
知道在恒定压强下,体积如何随着温度变化。
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so that's what we think we know in constant pressure calorimetry.
好，我想这就是我们,在恒压量热法中所知道的。
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This depends on the path. It tells you right here the path is constant pressure. These don't depend on the path, right. V doesn't care how you v get there. u doesn't care how you get there.
这由变化的具体路径决定,这个小脚标表明过程是恒压的,这些量都与具体路径无关,即不管是通过什么路径使得体积变化为Δ
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You're running some reaction. It's in the atmosphere. It's at constant pressure.
你已经在进行一些反应,在大气中，在恒温下。
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dV dT Is equal to minus dV/dT at constant pressure.
它等于，负的恒定压强下的。
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It's going to take place in there. It's going to be a constant pressure, it might be open to the air, or even if it isn't, there might be plenty of room, and it's a liquid anyway, so the pressure isn't going to change significantly.
也许它是液体，它在这个位置,这是恒压的，它也许是连通大气的，就算不是，它也有，足够的空间，而它是液体,压强不会显著地改变。
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Could be done, but easier is to just do the whole thing at constant volume, right, and just run the reaction that way and redo the calculation to be a constant volume rather than constant pressure calorimeter, right.
可以进行测量,但是如果在体积恒定的条件下,做这些会容易得多,还是这样进行反应,但是在等体而不是恒压条件下重新计算。
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So that's going to have to be a constant pressure path.
它应当包含,一个等压过程。
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dG/dT That is, this is, dG/dT at constant pressure.
这就是恒定压强下的。
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Whereas, like isobaric means constant pressure.
等压“指压强不变。
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p So dV/dT at constant pressure is just nR over p.
所以恒定压强下dV/dT等于nR除以。
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Let's label that two. It's still at constant pressure.
我们把这个标为II，它仍然是在恒压下。
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T So we know that T dS/dT at constant volume is Cv over T, T and dS/dT at constant pressure is Cp, over T.
在恒定压强下定压比热容Cp乘以dT除以,所以在恒定体积下dS/dT等于Cv除以，在恒定压强下dS/dT等于Cp除以。
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Let's take a system. Under constant pressure T1 V1, going to a second -- this is the system, so let me write the system here.
我们建立一个系统1,在恒定的压强T1，V1，下，变成了另一个系统，-这个初始的系统让我把它写在这。
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