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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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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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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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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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Normally this is used for a reaction in the condensed phases and liquid usually.
通常它是用于凝聚态，液体相的反应,这是一个恒压量热计。
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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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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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it's zero. Delta H1 is zero, right.
处于恒压下，它是零。
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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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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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We already did that. OK, dH/dT constant pressure is Cp. That was easy one.
我们已经做过这个计算了，好的，在恒压,状态下的偏H偏T就是Cp，这个很简单。
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Adiabatic q equal to zero. It's also delta H 0 which is zero. The two didn't necessarily follow because remember, delta H is dq so p is only true for a reversible constant pressure process.
在这个过程中ΔH等于,绝热的所以q等于0，而ΔH也等于,这两个也不一定有因果关系,因为，记住，ΔH等于dq只有在恒压。
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Over here, we have dq=Cp dT, the heat, the proportionality between heat - and temperature rise is given by this, the constant pressure heat capacity.
这里我有dq=CpdT，这是热量，这是联系热量,和温度变化的系数，恒压热容。
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dT That means that dH is also equal to dH/dT, constant pressure dT. All right, so now I've T ot more dH/dT under constant pressure.
也等于偏H偏T恒压乘以，现在我已经得到了在恒压,状态下的偏H偏。
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The constraint isn't constant temperature because the temperature is going to be changing.
是在不停变化的，不是恒压,因为我们已经有Δp了。
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T Remember, we're trying to get delta H, p we're trying to get dH/dT constant pressure and dH/dp constant temperature. OK, these are the two things were trying to get here.
想要得到在恒压状态下的偏H偏，和在恒温状态下的偏H偏,好的，这是两个我们，在这里想要得到的东西。
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