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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Another experiment would be to mix two chemicals together and put a thermometer in and measure the temperature.

比方说做这样一个试验,将两种化学试剂混合然后测定反应温度

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And so an experiment said the gas didn't increase its temperature when it expanded the vacuum.

这个实验告诉你,气体在向真空膨胀的过程,中温度没有升高。

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Joule actually did this experiment, and he observed that for the gas expansions that he could do, that the temperature did not increase measurably.

事实上焦耳的确做了这个实验，他做到了,他能达到的最好实验要求，发现在可测量范围内没有观察到温度上升。

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It's tabulated in books, and this we can measure p in the experiment. Delta p here is the change in pressure from the left side to the right side, and we can put a thermometer, measure the temperature before the experiment and measure the temperature after the experiment.

这列在书上，这个量我们在,实验中也可以测量，在这里Δ,是从左边到右边的压强变化，我们可以放一个温度计，去测量实验前的温度,再去测量试验后的温度。

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This is real, unlike the Joule coefficient which is very small so that most gases have tiny Joule coefficients. So if you do a Joule experiment, you hardly measure a temperature change. With real gases, here you do actually measure it. You can feel it with your finger on your bicycle tire.

系数那样小以至于,大多数气体的焦耳系数,都很小，所以如果你做焦耳实验,很难测量出温度的变化,对于真实气体，你可以测量它，你能通过手指按在,自行车轮胎上来感觉到它。

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p This is going to get us dH/dp constant temperature. What is this experiment?

这帮助我们理解恒温条件下的偏H偏,那么这个实验具体是什么呢？

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So in this experiment here, delta p is less than zero. You need to have this whole thing greater than zero. So delta T is less than zero as well. So if you're below the inversion temperature and you do the Joule-Thomson experiment, you're going to end up with something that's colder on this side than that side.

所以在这个实验中，Δp小于零,这全部都大于零,因此ΔT也小于零,所以如果在低于转变,温度的情况下做焦耳-汤姆孙实验,最后的结果是,这边的温度比这边低。

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