00:01
Asbestos, which was used for years as an insulating material in buildings, until we found out that it was demonstrated to cause lung cancer cancer, is a mineral that contains magnesium, silicon, oxygen, and hydrogen.
00:16
One form of asbestos called, i'm not sure to pronounce this, so i'm going to call it chrysotile, has 570 .27 molar mass.
00:34
And we're told that it has the following composition.
00:40
Magnesium is 28 .03%.
00:46
Silicon is 21 .60 % and hydrogen is 1 .16%.
00:59
I'm going to take all of these away from 100, 100 minus 28 .03.
01:08
Minus 21 .6, minus 1 .16.
01:15
And i get 49 .21%.
01:18
So i'm going to go 0 equals 100 minus 28 .03 minus 21 .60 minus 1 .16 equals 49 .21.
01:37
Okay.
01:49
Okay, now, in order to calculate our empirical formula, we're going to use our poem percent to mass.
01:57
So i'm just going to change these to mass.
02:04
Mass to mole.
02:05
So next i'm going to divide each of these by their molar masses to convert them to moles.
02:13
Whoops, see, where's my p table? i got the wrong periodic table up.
02:20
I just hate that.
02:23
Magnesium's 24.
02:24
I'm just going to go to two decimal places.
02:27
24 .31.
02:30
Silicon is 28 .09.
02:35
Hydrogens 1 .01 and oxygen is 16 .00.
02:40
These are only grams per mole, grams per mole, grams per mole.
02:55
Now i'm going to write these, i'm going to do the math and write each of these down.
03:05
First we have 1 .153 and that's magnesium.
03:20
This is 0 .769 moles of silicon.
03:37
This is 1 .149 moles of h.
03:49
And i have 3 .075 moles of o.
03:58
I'm going to write that one down here.
04:07
3 .075.
04:10
Then we divide by small and multiply till whole.
04:15
So i'm going to divide these all by the smallest number, which will be 0 .769.
04:36
That equals 1 .5, 1, 1 .5, and my other 3 .075 divided by point.
04:49
This will equal 4, divide by small, and multiply till whole...