00:01
There, in this question we are given a number of atoms, specifically of arsenic, but we'll get to that in a moment.
00:10
And what we're trying to determine is the mass in grams of this sample.
00:18
So we cannot, we don't have any way to convert directly from number of atoms to mass, but what we can do is go through the mole because we can convert from number of atoms to moles by using avogadro's number.
00:32
Avogadro's number tells us the number of representative particles in one mole of anything.
00:39
So in this question, we are working with the element arsenic.
00:45
So one mole of arsenic is going to contain avogadro's number of atoms.
00:50
And avogadro's number is 6 .02 times 10 to the 23rd.
00:55
So we would have that many atoms of arsenic for every mole of arsenic.
01:00
Then we can convert from moles to mass by using the molar mass.
01:05
Molar mass is the mass of one mole of a substance in grams.
01:09
We typically get that from the periodic table, but in this problem, they just gave it to us right here in the problem.
01:15
We're told that one mole is 74 .92 grams.
01:21
Okay, so now we have a plan and we have two equalities that we can use as conversion factors.
01:28
Let's go ahead and pull our starting value out of the problem and set this up and solve it...