00:01
Okay, so we're wondering, for every gram of propane, what volume of air is needed to burn it completely? so, it looks like our temperature is given as 205 degrees celsius, which we're going to convert to kelvin plus 273 kelvin.
00:24
We'll make it into, what, 478 kelvin? then, you know, that pressure is 1 .2 a .0 atmospheres, and mole fraction of 02 is 0 .2.
00:51
Okay.
00:53
So basically what we're doing here is we are solving this equation for volume.
01:07
N -r -t over p.
01:11
Okay.
01:13
So the first thing we need to figure out is let's just write down this equation real fast.
01:21
Sorry, i'm having trouble scrolling down.
01:25
I don't know why.
01:29
Okay.
01:30
I think i figured out.
01:32
Let's write down this equation.
01:38
So c3h8 plus o2 makes c -o -2.
01:45
And water, right? okay.
01:51
So what that means is if we balance this thing out, which is looking kind of terrible, but we'll deal with it anyway.
02:01
Okay, that gives us six, ten oxen.
02:04
Okay, gotcha.
02:06
Okay, so look at this.
02:07
We have three carbons, one, two, three, one, two, three, and then eight hydrogens, and then ten oxygens.
02:16
So that's perfectly balanced.
02:17
Okay, so for every gram of propane, we're trying to figure out how much air we need.
02:23
So, one gram of c3h8, one gram of c3h8, and then we know that the molar mass of propane is 36, which is 3, hydrogen, sorry, so 44 grams per one mole of c3h8.
02:58
And then we know that for every one mole of c3h8, we need five moles of o2.
03:08
So basically what i'm doing here is trying to get to moles of oxygen because we're given pressure, we're given temperature, and the only one we don't know is n.
03:20
And what does that n need to be? it needs to be whatever gas we're talking about under these conditions.
03:26
And so that gas is oxygen.
03:31
So when we solve this, we get 1 divided by 44 times 5.
03:41
So we need 0 .1136 moles of 0 .2.
03:47
And we don't need moles of propane here because what we're trying to figure out is the volume of air, volume of air.
03:56
But this isn't that volume of air.
04:01
This is the volume of the o2, because all these things are about o2.
04:06
So once we have volume o2, we can use the mole fraction to figure out everything else, to figure out basically how much air we need, if that makes sense.
04:20
Okay, so now we have all these numbers.
04:22
We know that volume is going to be equal to n 0 .1136 moles.
04:28
Times r, 0 .0826 liters times atms over moles times kelvin, and temperature, which is 478 kelvin, all this over the pressure, which is 1 .2 .0 .0 .80.
04:50
Okay.
04:52
So, we're going to do this...