00:02
In problem number 14, we want to derive an equation for density and its relationship to volume or to temperature and pressure from the ideal gas law.
00:16
So let's write out the ideal gas law.
00:18
Remember it is pv equals nrt.
00:23
Let's also remind ourselves that density is equal to mass divided by volume.
00:35
So in the ideal gas law equation, we already have volume.
00:39
But in order to get density in here, we need to get mass in here somehow.
00:46
Well, if we think about molar mass, i'm going to abbreviate molar mass with a capital mm.
00:53
Remember, molar mass is grams per mole.
01:02
Or if we think about it, grams is mass, and mole, as far as the ideal gas law is concerned, is n.
01:12
So molar mass is mass divided by n.
01:16
I want to rearrange this equation to solve for n.
01:21
So when i do that, the number of moles is going to be equal to mass divided by the molar mass.
01:31
So this is something i can put into the ideal gas molecule equation now.
01:35
So pv equals instead of n, i'm going to put mass over molar mass times rt.
01:50
All right, so we want to get density.
01:53
Density is mass over volume.
01:56
So we need to do some rearranging here...