for instance, for the thermos with the coffee in if you place the boundary in the inside wall of the glass or the outside wall of the glass and the inside of the thermos, that makes a difference; different heat capacity, etcetera.

比如说，对于装咖啡的热水瓶来说,你把边界设置在瓶胆的内壁上,或者设置在瓶胆外壁上,或设在热水瓶里面，情况都是不一样的;,有不同的热容等等。

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