So, the formula for enthalpy is usually written as change in enthalpy.

因此，的公式通常写成变。

And we measure enthalpy with a weird little science called calorimetry.

我们用一种叫做量法的奇怪小科学来测量。

Why enthalpy change is different from heat, even though they turn out to be pretty much the same anyway.

为什么变与不同， 尽管事实证明它们几乎是一样的。

Those bonds are nothing but energy, and using enthalpy, we can measure how much energy they have.

这些键只不过是能量， 使用，我们可以测量它们有多少能量。

Change in enthalpy is equal to the heat gained or lost by the system.

变等于系统获得或损失的量。

The law itself says nothing about the standard enthalpy of formation.

该定律本身并未提生成。

So I guess in the capital H for enthalpy does kinda make sense.

所以我想在大写的 H 中表示确实有点道理。

So, I wonder how that compares to the amount we would predict using Hess's Law and the standard enthalpy of formation?

所以，我想知道这与我们使用赫斯定律和生成预测的量相比如何？

Hess' Law is often stated in terms of standard enthalpies of formation.

赫斯定律通常用生成来表述。

As long as you start with the same reactants and end with the same products, the enthalpy change is the same.

只要您从相同的反应物开始并以相同的产物结束， 变就相同。

Thanks to many hardworking chemists, the standard enthalpy of formation has been measured for hundreds of compounds.

感谢许多辛勤工作的化学家，已经测量了数百种化物的生成。

It's analogous to the standard enthalpy of formation that we use to calculate change in enthalpy.

它类似于我们用来计算变的生成。

These measurements are done at standard conditions, which we discussed in the enthalpy and entropy episodes.

这些测量是在条件下完成的， 我们在和熵情节中对此进行了讨论。

Hopefully that sounds like fun because more about the ins and outs of this are coming in an episode on how to measure enthalpy.

希望这听起来很有趣，因为有关如何测量的一集中将详细介绍这方面的来龙去脉。

And I'm very happy the inventors knew how to calculate the enthalpy change of chemical reactions.

我很高兴发明者知道如何计算化学反应的变。

In order to study this stuff carefully, he looked at the standard enthalpies of formation of the reactants and the products of a reaction.

为了仔细研究这些东西，他研究了反应物和反应产物的生成。

Note that the standard enthalpy is in kilojoules while the standard entropy is in joules per Kelvin.

请注意，的单位是千焦耳， 而熵的单位是焦耳每开尔文。

So there you go, the calorimetry formula gave an absolute enthalpy change of 6.2 kJ, while Hess's Law gives a change of 5.67 kJ. So, why the difference?

所以你走了，量法公式给出了 6. 2 kJ 的绝对变， 而赫斯定律给出了 5. 67 kJ 的变化。 那么，为什么不同？

Hess's law says that the total enthalpy change for a reaction doesn't depend on the pathway it takes, but only on its initial and final states.

赫斯定律说反应的总变不取决于它所采用的路径，而只取决于它的初始和最终状态。

Since absolute enthalpy is unknowable though, we have to be measuring from a baseline, and that baseline is that individual elements' most stable form at standard state.

由于绝对是不可知的， 我们必须从基线开始测量，而该基线是单个元素在状态下最稳定的形式。