00:03
In this video, we're going to be calculating the molar mass of oxygen gas, o2, methane, ch4, and ibuprofen, c -13, h -18, o2.
00:15
So when you go to calculate molar mass, the first thing you need to do is identify what elements you have present in your compound.
00:24
So in o2, we only have oxygen.
00:34
Next, we need to determine how many oxygen moles we have in o2.
00:42
So the subscript 2 tells us we have two moles of oxygen and oxygen gas.
00:51
Next, we need to multiply by the atomic mass of our element.
00:56
So in this case, oxygen.
00:58
So to find that, you'll look at the periodic table, and it'll be the number below the element symbol.
01:04
It changes depending on what periodic table you're looking at just because of rounding.
01:13
The periodic table i have gives 15 .999 grams per mole.
01:38
You multiply across.
01:41
In this case, we get 31 .998 grams per mole.
01:53
And because this was our only element in this chemical formula, this is our final answer for the molar mass of oxygen gas.
02:17
Now moving on to methane, we see we have ch4 as the chemical formula, which means we have the carbon and hydrogen atoms present.
02:34
We'll look to the subscripts to see how many moles of each are in this chemical formula.
02:40
There's no subscript next to carbon, which means we just have one.
02:47
There's a subscript of four to the right of our hydrogen, which means we have four moles of hydrogen in this formula.
02:56
We'll then go ahead and multiply by the atomic mass of each.
03:04
So if you look below the element symbol for carbon on the periodic table, you'll see the atomic mass is somewhere around.
03:13
12 .011, depending on how many decimals your periodic table rounds to.
03:30
And the atomic mass for hydrogen that we found on the periodic table should be somewhere around 1 .008 grams per mole...