00:01
We are given a 0 .4987 gram sample and it contains carbon, hydrogen, and oxygen.
00:16
Upon further analysis for co2 and h2o, we have 0 .9267 grams of co2 and 0 .1897 grams of h2o.
00:46
And it contains, so my oxygen will be, we'll have to do some calculations here.
01:04
There's a little poem i teach my kids, i'm sure you've heard it.
01:07
It's percent to mass, mass to mole, divide by small, multiply till whole.
01:13
This is our mass, so we've already done percent to mass, now we're going to do mass to mole.
01:19
We know that 44 .01 grams of co2 contains 12 .01 grams of carbon.
01:25
And we know that 18 .02 grams of h2o contains 2 .02 grams of hydrogen.
01:35
I guess this is going to be my mass first, so i need this mass.
01:44
So 0 .9267 times 12 .01 divided by 44 .01 will give me 0 .253 grams of carbon.
01:59
Let's see, and then i'm going to take 0 .1897 times 2 .02 divided by 18 .02 and that will be 0 .02126 moles of h.
02:36
Okay, two five two eight.
02:40
Now for my hydrogen, my oxygen, i'm going to take 0 .4987 grams and i'm going to subtract from that 0 .253 grams and 0 .0212 grams and this will equal my mass of hydrogen, excuse me, oxygen.
03:08
And i'm going to make this 0 .25, 0 .23, 25, 2529.
03:23
Okay, 2529 minus 0 .02126 will equal 0 .22454 and this should be grams of o.
04:01
So i have 0 .22454 grams of o.
04:08
I have 0 .02126 grams of h...