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I'm going to write it like this three moles of hydrogen which is a gas one bar 100 degrees Celsius.
我会写成这样：,三摩尔氢分子，气体,1巴，100摄氏度。
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For a real gas it depends on more than the temperature STUDENT: Are there any other constraints similar to that .
而对实际气体，这是不对的,它的内能不仅仅依赖于温度,学生：有其他,类似的约束吗？
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So do you think noble gases would have a high positive electron affinity, a low positive, or negative electron affinity?
那么，你认为稀有气体的电子亲和能,应该是一个高的正值，一个低的正值，还是一个负值？
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He had a tube with electrodes potted in it filled with atomic hydrogen. And by applying a voltage, he was able to get the gas to glow.
那是个装满了氢原子并含有电极的管子,通过增加一个电压，他让气体燃烧起来了。
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If you start segregating the gases, there are fewer possible configurations that because you're forcing a particular set of circumstances.
如果你开始分离这些气体，整个系统所具有的可能的状态就会变少,你强加了一个特定的条件。
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So when I expand this gas adiabatically and it cools down, why do you think it might cool down?
现在我们知道了气体绝热膨胀时,温度会下载，为什么会降温？
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OK, this is only true for an ideal gas, and we went through that mathematically where the, with a chain rule.
这一关系只对理想气体成立，上节课我们,用链式法则推导出了这一关系。
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pV=RT dT here because the pressure is constant, dV=RdT/p so dV is equal to R over p dT.
因为对1摩尔气体有，于是。
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I left out the noble gases here because they do something a little bit special, and actually, I'm going to give you one last clicker question today to see if you can tell me what you think noble gases do.
我并没有把稀有气体算在里面,因为它们的电子亲和能有点特别，实际上，我将会把这作为今天的,最后一个选择题，来请大家告诉我,你们觉得稀有气体电子亲和能应该是怎样的。
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This is the diagram taken right from your text, there are the two electrodes coming in and this is atomic hydrogen in the gas tube.
这是从教科书上复制下来的图表，这里有两个电极进来,这是气体管中的氢原子。
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Versus looking at, for example, helium or neon or argon, these are all inert gases, inert meaning essentially do not react, those were grouped together in the periodic table.
相反，他发现氦，氖，氩，都是惰性气体，惰性的意思是基本不参与化学反应，因此把它们放在周期表中的同一类里。
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You take fuel, rather you take something that's warm, and you put it in contact with the atmosphere, it cools down.
改变约束,继续加热,气体膨胀。
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This needs to be stressed that this is the ideal gas case. Now regular gases, real gases fortunately as I said, don't obey this.
需要强调的是这是对理想气体而言的,普通气体，真实气体，就像我说过的,不遵循这个规律，这是非常重要的。
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This is the fact that we occupy a finite volume in space, because they're little hard spheres in this molecule.
这是由气体分子在空间中,占据有限体积造成的,因为事实上它们是硬的小圆球。
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So let's take our one model that we keep going back to Equation of state, and just see how it works.
我们回到经常使用的理想气体模型,或者说状态方程。
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And we saw that in fact in this case delta S of mixing, we calculated it, saw that it is positive.
实际上如果我们计算气体混合过程中,熵的变化，我们会发现这个量是正的。
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Now, we saw before, or really I should say we accepted before, that for an ideal gas, u was a function of temperature only.
我们已经看到,或者说我们已经接受这样一个事实，即理想气体的内能只和温度有关。
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You're allowed Cv comes out here for this adiabatic expansion, which is not a constant volume only because this is always true for an ideal gas.
绝热过程写下,这个式子是因为它对理想气体都成立，并没有用到等容过程的条件,只用了理想气体的条件。
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So, clearly, if we remove this barrier mixing takes place and obviously you know that that happens from lots of experience.
所以很明显，如果我们拿走隔板,气体混合就会发生,我们从大量的实际经验中就可以知道这些。
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But if you touch the valve going into your tire which basically measures the temperature of the air going into your tire, that is getting hot, right.
以至于浑身发热,如果你摸气筒的阀门,相当于近似测量了进入轮胎的气体的温度，它会很热，对吧。
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This quantity is exactly zero for an ideal gas and we'll discover why eventually it has to do with what we mean by an ideal gas it turns out.
对理想气体它是零,这点我们接下来会知道是,为什么，这与为什么我们叫它理想气体有关。
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All right, then as I push through, I'm going to start with all of my gas on this side, and at the end I'm going to have all the gas on the other side.
好的，随着我的推动,刚开始这些气体全在这一边,到了最后，这些气体全在另一边。
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Here just two, so we changed the number of moles of gas by three. All right, how much did it matter, right?
所以我们将气体的摩尔数,改变了3摩尔，好，它会起多大作用？
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So the work that you're doing to expand, to go through this experiment, ends up cooling the gas.
因此在膨胀气体的过程中,气体降温。
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So that you could see that for the ideal gas, u would not be a function of volume, but only of temperature.
所以我们可以看到对理想气体，内能不依赖于体积，而仅仅是温度的函数。
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I want to cool a gas with a Joule-Thomson experiment, what temperature do I have to be at?
给气体降温时,需要到达什么温度？
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So, you do this measurement, you measure with the gas, you measure the pressure and the molar volume.
现在让压强趋于，现在测量气体的压强，和摩尔体积。
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So for an ideal gas, we saw that u was only a function of temperature.
对于理想气体，我们知道内能只是温度的函数。
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And so now, instead of using these reference points for the Kelvin scale, we use the absolute zero, which isn't going to care what the pressure is.
就像理想气体温标,与气体的种类无关一样，具有普适性，在开尔文温标中。
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In other words, we're taking advantage of the fact that we now know that quantity. In the case of the ideal gas we just have a simple model for it.
换句话说，我们可以利用我们已经,了解这个物理量的这个优势,对理想气体我们有一个简单的模型。
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