[Jonath198]

Hey guys, I'm having problems with this question involving Mole conversions. I don't know whether or not it's stoichiometry. Hopefully someone can help me out. Thanks in advance.

How many molecules of (NH4)3PO4 are there if we have 1.25 x 10^23 atoms of O?

[Arkcon]

Welcome, Jonath198: to the Chemical Forums.  According to the Forum Rules{click}, we want to see your attempt.

Can you use Avagadro's number to start to solve this one for yourself?

[Borek]

Hint: how many O atoms in a molecule of (NH₄)₃PO₄?

And no, you don't need Avogadro's number, you don't even need to know what a mole is. I guess Arkcon misread the problem as asking about the number of moles of ammonium phosphate when it asks just for a a number of molecules.

[Arkcon]

Whoops.  That was silly of me.  If there's more questions, you might need my hint.  But no, not as written. 

[Jonath198]

Ughh why can't I figure this out.

This is what I got so far.

1.25×10^23/6.022×1023
= 0.2075mol

[Borek]

I told you - there is no need for moles nor Avogadro's number.

Have you seen my earlier hint?

How many bicycles are there in the shack, if there are 20 wheels?

[Jonath198]

So I would just divide 1.25 x 10^23 by 4? 0_o

[Borek]

Yes, it is that simple.