So, and of course, you know, keeping entropy as a fixed variable for a system like that is extremely cumbersome.
所以,对这样的系统要求它们的熵保持恒定,和一个非常笨拙做法。
To ask questions like how much heat is released in a chemical reaction that takes place at constant temperature.
当我们想要知道,当一个化学反应在恒定的温度下发生时,会放出多少热量时。
Or another way of saying it is, we're going to use as the basic steps, those operations that run in constant time, so arithmetic operations.
我们用可以在恒定时间内完成的操作,算法,比较,内存读取。
The angle is increasing at a steady rate, so we know it's going at a steady speed.
转过的角度以恒定速率增加,所以我们知道它以一个恒定的速度运动
Well that process of control to maintain a constant environment inside our body, whether it's an environment of constant mass or constant composition, or constant temperature, is called homeostasis.
这个控制过程维持着,体内环境的恒定,不论是内环境中物质的量的稳定,或者成分的稳定,或温度的稳定,这种状态叫做内稳态
Whereas under these conditions, these quantities, if you look at free energy change, for example at constant temperature and pressure, H you can still calculate H.
但是,在这些条件下,这些物理量,如果我们考察自由能的变化,例如在恒定的温度和压强下,我们仍然可以计算。
And in particular let's look at, for example, du/dV du/dV at constant temperature.
更特殊一点考察,恒定温度下的。
dS/dV And that, now, we know must equal dS/dV, with a positive sign. At constant temperature.
我们知道这个等于恒定温度下的,符号为正。
So this is still adiabatic. It's insulated, but now it's constant volume, OK.
这仍然是绝热的,是隔热的,但现在它的体积是恒定的。
So let's see. The first line, that print thing, is obviously constant, right?
显然是恒定的,对吧?,就把他当成一些固定的操作?
This particle is constantly changing its direction, but it therefore has an acceleration and the acceleration, we have shown here, is pointing towards the center.
这个质点恒定地改变它的运动方向,因此它具有加速度,而且这个加速度,我们前面也讲过了,指向圆心
Now, you know with constant volume, H now it's not going to be delta H that's U straightforward to measure, it's going to be dealt u, all right.
好,现在你们知道在体积恒定的条件下,我们得到的不是Δ,我们直接测量到的是Δ,好,但这基本上也是一样的。
It's a state function, so we're at constant temperature and pressure, and now we want to consider some chemical change or a phase transition or you name it.
这就是态函数,我们处于恒定的温度和压强之下,然后考虑某些化学变化或者相变,或者你想考虑的东西。
And so, again, we see a temperature increase, and we know the work, and the temperature increase, it's a constant pressure thing.
好,我们看到温度升高了,然后我们有做功量和温度的升高量,这是一个恒定压力下的值。
OK, so we have constant temperature, because it's isothermal.
好,现在系统有恒定的温度,因为它是绝热的。
Because so much of what we do in chemistry does take place with constant temperature and pressure.
因为化学中我们所做的很多东西,都是在恒定的温度和压强下进行的。
You know how pressure changes with temperature at constant volume if you know the equation of state.
如果你知道状态方程,知道在体积恒定的时压强如何随着温度变化。
p Well, it's not just p dS/dV because there's some dS/dV at constant T.
它不是简单的,因为式子中还包含,恒定温度下的。
That is, it's easy to write down straight away that dG with respect to temperature at constant pressure S is minus S.
这就是说,可以很简单的写出dG在,恒定压强下对温度的偏导数,是负。
V So this nR over V. And then, using the relation again, T we can just write this as p over T.
恒定温度下的dp/dT等于nR除以,再次利用状态方程,可以把它写成p除以。
A It tells me that the partial of A with respect to T at constant V is minus S. Right?
他告诉我们,在恒定体积下对温度的微分等于负S,对吗?
There's our condition for equilibrium at constant temperature and pressure.
这就是我们在,恒定温度和压强下的平衡条件。
dV dT Is equal to minus dV/dT at constant pressure.
它等于,负的恒定压强下的。
Yes, and if we have gases involved, it's pretty similar, but now what will have is something like this. We'll have a reaction vessel that's sealed, it's constant volume.
如果涉及了气体,情况也很相似,只是现在的装置是这样的,我们有一个密封的反应容器,它的体积是恒定的。
If I'm the system, what's constant when I do this?
什么量是恒定的?有人有什么想法吗?
First, we got to make sure the spring exerts a fixed force every time.
首先,要保证,弹簧每次产生的力是恒定的
SV And this is, of course, with constant S V.
当然在这里是保持恒定的。
Well, we already know what dA/dT at constant V is.
我们知道恒定体积下的。
First, free velocity, constant velocity can be obtained for free without doing anything.
首先,速度是无偿的,恒定速度不需外力作用就能无偿获得
dG/dp And this is dG/dp at constant temperature.
这是恒定温度下的。
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