00:02
Hi there.
00:03
In this question, we have a 4 .8 gram sample of aluminum sulfate, which has the formula al2 -s -o -4 -3.
00:17
And we want to know the mass of the oxygen in the sample.
00:22
Well, we see that in every al2 -s -o -4 -3, there's three times four or 12 oxygen atoms.
00:31
All right, so we're going to use that.
00:33
We're going to do a series of calculations here.
00:35
And the first thing i want to do is to convert to moles of this compound.
00:40
So i need the molar mass of aluminum sulfate.
00:42
Adding together the mass of two aluminum, three sulfur, 12 oxygen, gives me 342 .14 grams of the aluminum 2 sulfate.
00:59
That's in every mole of it.
01:08
Okay.
01:10
Next, then, i want to talk about those 12 oxygen that are in every one of these...