View Full Version : Quick moles problem
Attraction
Jul10-09, 12:29 PM
1. The problem statement, all variables and given/known data
If you have 4.5 x 1020 molecules of SnO2, how many moles of O do you have?
3. 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
Jul10-09, 12:33 PM
Simple unit conversion and seeing the ratio of items. You need to know the meaning of a mole.
Attraction
Jul10-09, 12:47 PM
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.
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?
Attraction
Jul10-09, 01:28 PM
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?
Attraction
Jul10-09, 01:50 PM
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
Jul11-09, 09:45 PM
Finally, Yes.
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