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But we've defined the enthalpy of those elements in their stable state at room temperature and pressure as zero, right?
但我们已经定义了这些,元素处于它们室温和常压下,最稳定的状态时的焓为零，对吧？
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OK, for most gases, T inversion is much 300K greater than 300 degrees Kelvin. Much greater than room temperature.
好，对大多数气体,转变温度都高于,比室温高很多。
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If you have a large number of atoms in an aggregate, it is going to require that the substance turn solid and condense at room temperature.
如果有很多原子进行聚集，在室温下,会使的物质转变成固体状态。
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So if you had a jar full of triglycerides it would behave like an oil, many would be liquid at room temperature.
所以如果你有一满瓶甘油三酯,它看上去就好像油一样,它们在室温下都是液体
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What we define as zero is the enthalpy of every element in its natural state at room temperature and ambient pressure.
我们将零点定义为每种元素,在室温和正常大气压下,在其自然状态下的焓。
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And it's not hard to see how the heat of reaction at room temperature can be related to they heat of reaction at other temperatures.
知道室温下的反应热,如何与其他温度下的反应,热联系起来这点并不困难。
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Hydrogen gas it's in its most stable state, right at room temperature and pressure.
和常压下氢气是氢元素，最稳定的状态，这个小“0“
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And then maybe I raise the temperature to whatever, room temperature, maybe 20 degrees hotter than room temperature. And I again say OK, now how much heat do I need to raise this thing's temperature by 1 degree?
我可能把温度升到，比如室温,或者比室温高20度之类,然后我再说，好,现在要把这个东西的温度,升高一度需要多少热量？
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HBr They form HBr which is a gas at room temperature and one bar, right.
和常压下是液体，它们生成了,在室温和1巴下是气体。
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And I didn't specify the conditions, but if we were to do this under ordinary chemical conditions of some, you'd say room temperature and pressure, right, they all happen spontaneously.
我并没有特别说明反应条件，但是如果我们在通常的化学条件下,实现这些化学反应，比如在室温和大气压下下，他们都是自发的。
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Now in this particular reaction, I've got hydrogen gas, iron solid. Those already are elements in their most stable forms at room temperature and pressure.
特定的反应中，我有氢气,固态铁，这些都已经是,处于室温和常压下,最稳定的元素单质。
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Delta H of formation means the enthalpy of this compound minus the enthalpy of its constituent elements in their most stable state at room temperature and pressure.
生成焓就是这种组分,的焓减去它的所有组成元素,在室温和常压下处于,其最稳定的状态时的焓。
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Iron as an element is a solid. That's it's most stable state at room temperature and pressure, right, and so on. And then we can figure out heats of formation.
铁单质是固态,这是他在室温和常压下,最稳定的状态，然后我们,可以算出生成热，现在这个。
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We use a liquid helium. And so in order to make a liquid helium, you can't take helium at room temperature and do this, because if you did, you would just heat it up, because the room temperature is above the inversion temperature, so Joule-Thomson would heat up the helium.
为了得到液氦,不能再常温,做这个实验,否则就是加热氦气，因为室温高于它的转变温度,所以焦耳-汤姆孙，实验会加热氦气。
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Or in many kinds of gas refrigerators where you push a gas through a nozzle close to room temperature, what you find is that the gas coming out on the other side under lower pressure is cooler than the gas that went through on the other side.
或者在很多种压缩气体式冰箱中,你让气体通过接近室温的管口,你会发现从压力低的一边,出来的气体比通过,另一边的气体更冷,真正的冰箱实际上通过。
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You take your room temperature liquid helium and you cool it with liquid nitrogen to 77 degrees Kelvin, the new, you're not quite there yet 77k unfortunately right? Then you take hydrogen you cool it would liquid nitrogen to 77, then you can use your hydrogen gas.
首先要有常温的氦气,拿液氮把它冷却到77k，那个新来的7,你不坐在那儿，对吧？,然后用液氮把氢气降温到,然后就可以使用这个氢气了，想要用氢气来做焦耳-汤姆孙实验。
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When you go from here to going outside, to going to a much hotter room, your temperature stays the same and your body is able to control this on your own, you don't have to think about it.
当你从这里走出去,去一个更热的房间的时候,你的体温不会变化,你的身体能自行控制体温,你无需要刻意想它
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Maybe you don't control thermostats in your dorm room, some of you do and some of you don't probably, and maybe it doesn't work very well so it might not be a good example, but imagine a perfect thermostat that you set for a temperature and then the temperature stays the same inside the room no matter what the temperature is outside.
可能你根本就不理卧室里的恒温器,有些人去调它,有些人就置之不理,可能它压根就是坏的,所以这个例子也许并不恰当,但你还是想象一个完美运行的恒温器,你设定温度后房间里的温度就保持不变,不管外面温度是多少
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You're running, you're shaking a beaker up here at room temperature.
你跑步，震动烧杯，这都是在恒定温度和压强的情况下的过程。
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6 It's got a density of about 1.76 at room temperature.
在室温下密度是1。
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They are solid at room temperature.
它们在室温下是固体。
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