## Homework E3

juliensantosdis3g
Posts: 2
Joined: Fri Sep 29, 2017 7:06 am

### Homework E3

"In a nanotechnology lab you might have the capability to manipulate individual atoms. The atoms on the left are gallium atoms (molar mass 70 g/mol), those on the right are atoms of astatine (molar mass 210 g/mol). How many astatine atomswould the pan on the right have to contain for the masses on
the two pans to be equal?"

I understood the given values of the problem. But I'm not sure how to start the problem. Would I convert the molar mass of astatine first or gallium?

Dylan Davisson 2B
Posts: 50
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 2 times

### Re: Homework E3

Since the question only asks you to find out how many atoms of astatine would be needed to equal the mass of the given gallium atoms, you don't technically have to convert anything.

Referring to the diagram below the problem, there are 9 gallium atoms of molar mass 70 g/mol. And since astatine's molar mass is 210 g/mol, it's atoms have three times the mass. This means that 3 astatine atoms would equal the mass of 9 gallium atoms.

(9 gallium atoms)(70 g/mol) = (x astatine atoms)(210 g/mol)
x astatine atoms = 3

Rachel N 1I
Posts: 48
Joined: Thu Jul 27, 2017 3:00 am

### Re: Homework E3

You can also think of this as a ratio. For one astatine atom there are 3 gallium atoms. Since there are 9 gallium atoms 9/3=3, there would be 3 astatine atoms.