# Quick moles problem

• Chemistry

## Homework Statement

If you have 4.5 x 1020 molecules of SnO2, how many moles of O do you have?

## The Attempt at a Solution

I'm really getting the hang of moles lately but what is bothering me in this question is 4.5 x 1020 molecules of SnO2.

If it was one molecule, you would have 2 moles of O yes?
Therefore in 4.5 x 1020 molecules, you have 4.5 x 1020 multiplied by 2? But that doesn't give me the correct answer.

symbolipoint
Homework Helper
Gold Member
Simple unit conversion and seeing the ratio of items. You need to know the meaning of a mole.

Simple unit conversion and seeing the ratio of items. You need to know the meaning of a mole.

Would I be right in saying that there would be 2 mols of O in ONE molecule of SnO2? I think so. So that would be 2 x Avogadros #.

Therefore in 4.5 x 1020 molecules of SnO2, there should be 2 mols of O x 4.5 x 1020 molecules? I know thats not right though. Where am I going wrong.

Last edited:
Borek
Mentor
Would I be right in saying that there would be 2 mols of O in ONE molecule of SnO2?

No. There will be two ATOMS of oxygen in one molecule on SnO2.

How many atoms per mole?

No. There will be two ATOMS of oxygen in one molecule on SnO2.

How many atoms per mole?

6.022x1023 per mole yes?, my problem is figuring out how many mols of O are in 1 molecule of SnO2.

So I must be wrong there with Avogadros number then?

Borek
Mentor
Yes.

I figured it out. Pretty easy. There is 2 atoms of O in the molecule. Therefore there is 2 x 4.5 x 1020 atoms in 4.5 x 1020 molecules... simple.

Then convert atoms into moles by dividing by avogadros #.

thanks.

symbolipoint
Homework Helper