00:01
Okay, in this problem, we have an ideal gas.
00:04
We have two moles of it.
00:06
It starts out at two atmospheres at a temperature of 127c, which is 400k, and a final pressure of four atmospheres, and a final temperature of 800k.
00:18
I've written down two different versions of the ideal gas constant over here, because we actually need both of them to finish this problem.
00:29
So, for part a, we want to know.
00:35
Know the initial volume.
00:37
So the initial volume we get from the ideal gas law is n times r times t i, initial temperature over pi.
00:48
Okay, so our pressures in atmospheres.
00:54
So it makes sense to use this version of r because it has atmospheres in it and k.
01:02
So my initial volume, if i substitute that in and all the other numbers comes out to be 37 .8 liters.
01:20
Part b, we want to find delta u.
01:25
So delta u is n c sub v delta t.
01:32
So here's the thing.
01:34
There's an assumption that we must make and i'm going to assume that c sub v is three halves r so that our gas has only one degree of freedom.
01:45
Okay, basically three degrees of freedom, x, y, and c motions.
01:50
So it's not a more complicated molecule than that...