Grams to Moles of Oxygen Gas

[Cecilia Cisneros 1F]

If we have a chemical equation that reads:
"H4 + O2 --> 2H20"
and we want to convert 2.54g of oxygen gas to moles in order to find the grams of H2O within the reaction. Would we use the molar mass of just "O" or of "O2"? As in either 16.00g/mol O or 32.00g/mol O2? Im a little confused because isn't oxygen gas "O2" and not "O"?

[Ximeng Guo 2K]

We should be using molar mass of O2, 32g/mol, to convert mass of oxygen(O2) into moles.

[Andrew Wang 1C]

Hi!
Since oxygen is one of the diatomic elements (along with Br, I, N, Cl, H, and F), it exists as O2. So when the question is talking about oxygen gas (O2), we should use 32.00 g/mol as a conversion factor.

Hope this helps!

[Sabine Salvucci 2E]

Since the problem is using oxygen gas (O2), we would use the molar mass for O2, 32.00g/mol.

[Cecilia Cisneros 1F]

Great thank you all!!

[Eva Becker]

Like everyone before has stated, 32g/mol would be the value in this context. I wanted to mention though that the reason we should use 32g/mol and not 16g/mol is because we have to take into account the mass of both atoms of oxygen (O2) which are present. This is important because, like Dr. Lavelle has mentioned while explaining why we balance chemical equations, mass can neither be created nor destroyed!

[SahajDole_1C]

You should use the molar mass of O2 because it is the molecule listed in grams, not O because the molar masses are different.

[Jordan Tatang 3L]

Like everyone else said you would be using 32g.mol^-1 since there are 2 Oxygen atoms in O2. Additionally, if the question asked to use H4 instead of O2 you would be using 4.032g.mol^-1 or (1.008g.mol^-1)(4) since there are 4 hydrogen atoms.

Hopefully that helps :)