"This is ground zero for the nation." Democrats in the state Senate fled to the neighboring Midwestern state of Illinois.
VOA: special.2011.02.25
But we've defined the enthalpy of those elements in their stable state at room temperature and pressure as zero, right?
但我们已经定义了这些,元素处于它们室温和常压下,最稳定的状态时的焓为零,对吧?
What we define as zero is the enthalpy of every element in its natural state at room temperature and ambient pressure.
我们将零点定义为每种元素,在室温和正常大气压下,在其自然状态下的焓。
Well, the energy at infinity is zero -K and the energy in the ground state is minus K.
无限远处的能量值为,而基态能量值为。
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。
There's no change in them, and then we also looked at some at non-state functions, work and heat, and saw that those aren't zero going around a cycle. Of course you can do work in a cyclic process, and heat can be exchanged with the environment at the same time.
它们不会有变化,然后我们研究了,一些非态函数,功和热量,并看到,沿着循环行进一周的话,它们并不是零,当然你可以在,一个循环过程中做功,而同时热量可以在系统,与外界环境之间进行交换。
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