00:01
So this problem gives us a number of atoms for a particular element and then wants us to find the mass in kilograms.
00:08
And so we'll start with letter a.
00:10
We have 7 .55 times 10 to the 26th cadmium atoms.
00:17
And so the first thing we'll do is divide by avagadro's number to get this into moles.
00:22
So 6 .02 times 10 to the 23rd atoms per mole.
00:26
And now that we have our answer in moles, we'll multiply by the molar mass, which for cadmium is 112 .41 grams per mole.
00:41
Now we have our mass in grams, but the problem wants the mass in kilograms.
00:46
So there's a thousand grams in a kilogram, and then grams cancel, moles cancel, and atoms cancel.
00:53
And we end up with the mass of 140 .9 kilograms of cadmium.
01:00
And that's our final answer for letter a.
01:03
Now we'll do the same thing for letter b.
01:06
This time we have 8 .15 times 10 to the 27th nickel atoms...