00:03
Hi there.
00:04
In this question, we are starting with a mass of a compound in grams.
00:10
And we're trying to convert to the number of specifically nitrogen atoms.
00:19
Right.
00:20
So the first thing we're going to need to do is to convert from that mass to moles.
00:25
And we can do that by using the molar mass.
00:28
The molar mass is the mass of one mole of the substance in grams.
00:32
So we can calculate that by using the periodic table.
00:36
So we have ammonium nitrate here.
00:40
Ammonium nitrate is going to be the ammonium ion, which is nh4, with the nitrate ion, which is n -o -3.
00:48
We have a one positive charge for ammonium and a one negative for nitrate.
00:52
So this formula is correct as written.
00:56
And to calculate its mass, we're going to need to add together the masses of each of these atoms in this formula.
01:02
That gives us 80 .05 grams.
01:05
So that is the molar mass of the ammonium nitrate.
01:15
Okay, so once we convert to moles of the compound, then we want to convert to moles of nitrogen.
01:25
And we're going to do that by using the formula.
01:29
For example, as we look at the formula for every mole of nh4, n .h4, n .3, we see that there are two moles of nitrogen, because there's one nitrogen in the ammonium and one nitrogen in the nitrate.
01:48
So there are two moles of nitrogen.
01:50
That will get us to moles of nitrogen.
01:52
And then finally we can convert to atoms of nitrogen by using avagadro's number.
01:59
Avagadro's number tells us the number of particles in one mole of anything...