How many moles of gas are there in each case, in reactants and products? If that changes, of course you know that the pressure in there is going to change at constant volume if the amount of gas in there is changing.

在反应物和生成物中，各有多少摩尔的气体？,如果它发生了变化,当然在等体条件下，如果气体的总量,发生了变化，压强也会发生变化。

麻省理工公开课 - 热力学与动力学课程节选

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。

麻省理工公开课 - 热力学与动力学课程节选

In other words, we choose a convention for the zero of entropy, so that then we can write entropies of products and reactants always referring to the same standard state.

换句话说，我们选择了一个,焓零点的约定，这样我们,就可以总是相对于同样的标准,状态写出生成物和反应物的焓。

麻省理工公开课 - 热力学与动力学课程节选

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。

麻省理工公开课 - 热力学与动力学课程节选

Of course, the cyclic steps that we've taken to do this apply not just for breaking down reactants and product into the elements in their standards states, but of course we could also look at whole sets of reactions and write cycles as well, right.

当然，我们这里用的循环的,步骤不仅仅在把生成物,和反应物拆成其标准状态下,的元素时有效,我们也可以研究整个一系列,反应并写出相应循环。

麻省理工公开课 - 热力学与动力学课程节选