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So by using the tabulated data, we can really determined heats of formation for most reactions that you might contemplate, OK?
所以，使用这些表格,我们就能确定大多数,你可能碰到的反应的生成热？
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You could run the reaction, take solid iron gaseous oxygen, form iron oxide, measure the heat of formation of it, tabulate it.
你可以进行一个反应,用固态铁和氧气生成氧化铁，测量它的生成热，列成表格。
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But this is a compound, right, it has some non-zero heat of formation from the elements. So is water, right?
但这是种化合物，对吧？,它具有非零的生成热,水也是一样，对吧？
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I didn't even need to know that heat capacity of the product, right. Because it's effect the thermal mass of the product is negligible compared to the thermal mass of the calorimeter.
我甚至不需要知道生成物的,热容是多少，因为生成物的,热质量的作用相比于,量热计的热质量是可以忽略的。
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So we're just subtracting, in effect, zero, right, from the enthalpy of the product, but of course it's important have that established because the heat of formation is something you could measure, right?
所以从效果上说，我们只是，从生成物的焓中减去了零，但，是确立这一点很重要,因为生成热是,你能测量的东西，对吧？
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So we don't really need to put in a certain amount of heat and change the temperature of the products and the calorimeter and so on.
所以我们实际上并不需要输入,一定的热量，改变生成物,和量热计的温度之类。
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So I need to find out the heats of formation of the iron oxide and the water.
所以我需要找出氧化铁和,水的生成热，如果我这么做了。
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Right? In other words I've got the stoichiometric coefficients in there and the values, and I'm subtracting the reactants from products -1652kJ/mol wind up with minus 1652 kilojoules per mole.
对吧？换句话说这里我用了化学,计量系数和生成热的值，从生成物中减去反应物,最后得到。
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Hf What's my heat of formation? Delta Hf.
生成热是什么？△
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This is the negative heat of formation, right?
这里是负的生成热，对吧？
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We can tabulate them. We can know them, and then when we have reactions that inter-convert different compounds, we can calculate the heat of reaction is just the difference between the heat of formation of the reactants, and the heat of formation of the products, right.
种化合物的生成热，可以把它们列成表,可以认知它们，而当我们要处理，在不同化合物间转变的反应时,我们只要计算反应物和,生成物的生成热之间的不同,就能计算出反应热。
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And if I do that then I can find out the change in enthalpy of this reaction. It's just going to be the heat of formation of these three moles of water, minus the heat of formation of the iron oxide. OK.
我就能得到这个,反应的焓的变化,它就是三摩尔水,的生成热，减去氧化铁的,生成热，好。
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It's just how much heat is involved when we change the temperature. Now, the products have some heat capacity associated with them right, it takes a certain amount of heat if we make their temperature change, to either put it in or take it away, depending on which direction the temperature is changing.
问题就是当我们改变温度时,有多少热量发生了转移,生成物具有一定的热容,如果我们改变,它们的温度，就要输入或,提取一定的热量,这取决于温度改变的方向。
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Fewer products and calorimeter at T1, right.
以及T1下的生成物和量热计，对吧？
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So here, I'm going to have delta H, is just the sum for all the products of delta heat of formation right? Here I'm going to put together all the products. So this is a positive heat of formation.
所以这里△H就是所有生成物的,生成热的和,对吧？这里,我要把元素组合成所有这些,生成物，所以这里是正的生成热。
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