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

因，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。

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量。

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

该定律本身并未提及标准生成。

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

所以我想在大写 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标准生成预测量相比如何？

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

赫斯定律通常用标准生成来表述。

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

只要您从相同反应并以相同产结束， 变就相同。

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

感谢许多辛勤工作化学家，已经测量了数百种化合标准生成。

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标准生成。

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

这些测量是在标准条件下完成， 我们在和熵情节中对进行了讨论。

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，因为有关如何测量一集中将详细介绍这方面来龙去脉。

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，他研究了反应和反应产标准生成。

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

请注意，标准单位是千焦耳， 而标准熵单位是焦耳每尔文。

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 绝对变， 而赫斯定律给出了 5. 67 kJ 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.

赫斯定律说反应总变不取决于它所采用路径，而只取决于它初和最终状态。

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， 我们必须从基线测量，而该基线是单个元素在标准状态下最稳定形式。