00:01
This question asks us to find the grams in a single atom for each of these two elements.
00:08
Now, what we're going to do first is we're going to go look at the periodic table, and we're going to go look at the molar mass.
00:15
So let's start with arsenic.
00:16
Arsenic's molar mass is 74 .9 grams per mole.
00:22
Now, this is the amount of grams in a single mole, but we need grams per atom.
00:30
So we need to do some converting.
00:32
And the conversion factor we need to use is that one mole equals 6 .022 times 10 to the 23 atoms.
00:46
It's also known as avogadro's number.
00:49
So we're going to set this up, and we're going to start with 74 .9.
00:56
I'll draw our dimensional analysis table grams per mole.
01:00
And now we know that one mole equals 6 .02 .2.
01:06
2 times 10 to the 23 atoms.
01:11
And so our moles cancel out...
