STP and Avogadro's Number - Question

[sdb09]

---

Members don't see this ad.

Hi -

I had a question about STP and the ideal gas law. On a Kaplan practice test I took, the question answer stated that "the number of atoms in 22.4 L of oxygen at STP" is NOT equal to Avogadro's Number.

I don't understand why this is not true. If you were at STP, and had 22.4 L, wouldn't that mean 1 mole oxygen and then 1 mole oxygen would be equal to Avogadro's number?

The explanation says that because oxygen is diatomic, there are 2 oxygen moles of oxygen atoms in the system and that one mole of oxygen atoms are found in 11.2 L of oxygen at STP. And that is why it is false?? But I am confused about the reasoning...

Thanks so much!

 

[Ninjaface]

There is one mole of oxygen molecules, each of which are composed of two oxygen atoms.

Brain fart?

😀

 

[StIGMA]

1 mole O=O (diatomic oxygen, gaseous at STP) is 2 moles Oxygen atoms.

Look at lewis structure for oxygen/O2