-
Now for this experiment, this is a constant enthalpy experiment for the Joule-Thomson experiment, this is equal to zero.
对于这个实验，焦耳-汤姆逊实验,是一个焓不变的实验,焓变化等于0，所以我可以。
-
And what we end up with for the energy then is 2.84 times 10 to the -19 joules.
我们算出的能量是,2，84乘以10的-19次方焦耳。
-
And the idea was that gravity did work on the water and falling, and that work led to the generation of heat.
焦耳的想法是,重力对水，做了功。
-
It is joules per atom. Or, if you multiply by Avogadro's number then you will get joules per mole.
焦耳每个原子，或者，如果乘以,阿伏伽德罗常数你会得到焦耳数每摩尔。
-
But it's a good story, Joule decided that there must be a direct relationship between work and heat.
所以说，这只是一个不错的故事而已，焦耳认为功和热之间,一定具有某种直接的联系。
-
One is that he observed when people were machining cannon barrels, a lot of heat was generated, and there was a lot of work done.
第一种说法说焦耳发现,制作加农炮筒时，会产生大量的热，同时这中间有大量的做功。
-
The relationship between heat and work was initially proposed in the 1940's by Joule.
热量和功的关系首先是,由焦耳在1940年提出的。
-
So if you're not in this 77%, let's quickly go over why, in fact, this is the correct answer, . 9 times 10 to the negative 18 joules.
如果你们不在这77%中，让我们快速的来看一看为什么，这个是正确答案，0，9乘以10的负18次方焦耳。
-
Also to point out, a lot of times you'll see electron volts instead of joules, this is the conversion factor here just so you all have it in your notes.
同样也要指出，很多情况下你会看到,电子伏特而不是焦耳，这里是换算因子,你们在讲义上都能找到。
-
And if you do so, you will end up with 1.312 mega joules per mole for this quantity K.
这样做之后，对于K常量你就能得到2,1。312百万焦耳每摩尔。
-
Real refrigerators actually work with liquids that go into gases so use the latent heat of the liquid, so it doesn't really work like the Joule-Thomson expansion. So this is real.
液体变成气体来工作,以运用液体的潜热，所以这不是,真正像焦耳-汤姆逊膨胀一样工作,这是真实的气体，不像焦耳。
-
But in terms of SI units, which become much more useful if you're actually trying to use intensity in a problem and cancel out your units, we're just talking about joules per second is what intensity is.
但是用国际单位制，这个变得越来越有用了,如果你实际上在使用强度,来解决问题和约化单位，我们仅仅讨论每秒钟的焦耳,这就是强度。
-
So, keep in mind that one milliwatt is just the same as saying 1 times 10 to the -3 joules per second.
所以，请记住1毫瓦,和1乘以10的-3次方焦耳每秒,的说法是等同的。
-
It turns out that this quantity here, which is called eta of J the Joule free expansion parameter, is not quite zero.
这个量后来被，称作焦耳膨胀系数,其实并不等于零。
-
What we've been talking about, the Joule-Thomson experiment, constant enthalpy process?
首先，刚才说的，那些有什么问题吗？,焦耳-汤姆逊实验，等焓过程？
-
Now you can see 2.18 times 10 to the minus 18 joules can be 13.6 eV.
你可以看到,2。18乘10到负18焦耳,得到13。6电子伏特。
-
That means our energy is equal to 6.626 times 10 to the -34 joules times seconds.
这意味着能量等于,6，626乘以10的-34次方焦耳每秒。
-
So for every photon we have 2.84 times 10 to the -19 joules.
每一个光子有,2，84乘以10的-19次方焦耳。
-
Occasionally, you'll find you need to cancel out units, because, of course, you're always doing unit analysis as you solve your problems, and sometimes you'll need to convert joules to kilogram meters square per second squared.
偶然地，你会发现需要消除单位，因为在解题时,经常要做单位分析，所以有时候需要把,焦耳换做,一千克乘以米的平方除以秒的平方。
-
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。
-
And then the conversion of joules to electron volts is entry 42. If you multiply those two together you will end up with this quantity.
然后焦耳和电子伏的转换,是在第42个常量，如果你把这两个放一起,你将得到这个数值。
-
And if that's equal to zero, that means that the Joule-Thomson coefficient for an ideal gas is also equal to zero. We're going to actually prove this later in the course.
说明理想气体的,焦耳-汤姆逊系数也等于0。,详细的证明过程,会在以后的课上给出。
-
So hopefully if some of you have your calculators with you, you can confirm the answer that I got, which is that the energy is 7.82 times 10 to the -19 joules.
所以如果你们带了计算器,希望你们也能确认一下，我们算出的答案，能量等于,7，82乘以10的-19次方焦耳。
-
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。
-
This one turns out to be the heat capacity, and this one turns out to be something that we measure in the Joule-free expansion.
其实，这就是热容，这是焦耳自由膨胀实验中,我们要测量的物理量。
-
OK, so we ended up last time, we talked about Joule-Thomson expansion, which is an irreversible expansion through a nozzle, through a porous plug, constant enthalpy expansion.
上节课，我们讨论了焦耳-汤姆逊，膨胀过程,也就是气体，通过毛细管。
-
Yeah, they're different but they are roughly on the order of about 1 MJ per mole.
是的，它们是不同的但它们大致上,都是一摩尔一兆焦耳。
-
And we saw that, you saw that the Joule coefficient for an ideal gas was zero.
我们会发现，你们也会发现,理想气体的焦耳系数是零。
-
it's kind of like the Joule expansion, an ideal gas.
焦耳-汤姆逊膨胀过程相似。
-
And we can go through and calculate the value of this quantity in parenthesis. And, when we do so, we get the value 2.18 times 10 to the minus 18 joules.
我们能进行计算这些值,如果我们这样做，我们能算出是，2。18，乘以10，的负18焦耳。
应用推荐