## HW Problem E17

Bryce Ramirez 1J
Posts: 120
Joined: Sat Aug 24, 2019 12:16 am

### HW Problem E17

In part C of this problem, it asks to compare which has the higher amount of moles. It gives 7.36 x 10^27 atoms of Ru and 7.36 x 10^27 atoms of Fe. I'm confused on how to convert this to moles because the question doesn't give us the mass, only the amount of atoms. The molarity for Ru is 101.07 g/mol and Fe is 55.85 g/mol.

Bryce Ramirez 1J
Posts: 120
Joined: Sat Aug 24, 2019 12:16 am

### Re: HW Problem E17

Nevermind, I think I just divide the atoms by Avagrados number to convert it to moles.

Katie Kyan 2K
Posts: 106
Joined: Fri Aug 09, 2019 12:16 am
Been upvoted: 1 time

### Re: HW Problem E17

Yes, you can convert the atoms to moles by dividing by Avogadro's number which is 6.022x10^23. Knowing that 1 mol Ru has 6.022x10^23 atoms of Ru, you can divide 7.36x10^27 by 6.022x10^23 to get the moles of Ru which is 1.22x10^4. Doing the same fo 7.36x10^27 atoms of Fe would show you that there are also 1.22x10^4 mol Fe. Thus, both samples contain the same number of moles.

Claire Stoecklein 1E
Posts: 49
Joined: Sat Jul 20, 2019 12:15 am

### Re: HW Problem E17

Number of moles is directly proportional to number of atoms, because Avogadro's number is a constant. Number of atoms has no relation to atomic mass.

Vicki Liu 2L
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

### Re: HW Problem E17

There are the same number of atoms, 6.022 * 10^23, in a mole of any element. Therefore, seeing that Ru and Fe are present in the same number of atoms, they should be present in the same number of moles as well.

Vicki Liu 2L
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

### Re: HW Problem E17

Also, by the way, in the last sentence, instead of "molarity" I think it should be "molar mass". Molarity refers to the concentration of a solution in mol/L. No big deal but just something to look out for!

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