00:01
All right, so let's say we have one mole of a diatomic gas, and we want to calculate the rotational kinetic energy of this gas at a temperature of 300 kelvin.
00:13
So there are two modes of rotation, and so are two degrees of freedom when we're talking about rotational energy.
00:22
And so f is going to be equal to two, and so two divided by two is just one.
00:26
So this is just going to be 8 .314 jules per kelvin times 300 kelvin.
00:36
So 8 .314 times 300 is going to give us 2494 .2 joules.
00:45
And that's part a.
00:47
Part b says to calculate the moment of inertia of an oxygen molecule, treating it as basically just two point masses separated by a distance of about 1 .2.
00:58
2 .1 times 10 to the negative 10th meters.
01:04
So the mass of each molecule, you know, the molar mass of oxygen is 16 grams per, or for oxygen and gas is 32 grams a mole.
01:16
But we're just looking at each atom.
01:18
So i guess we'll do 16 grams of moles to 0 .16 divided by 6 .02 times 10 to the 23rd.
01:24
So this gives us a mass per molecule of 2 .65.
01:29
2 .66, i guess.
01:31
We'll add it times 10 to the negative 26th kilograms...