atomic oxygen + water molecule = hydrogen peroxide?

[the guy]

would atomic oxygen react with a water molecule, on contact, to give hydrogen peroxide?

(if i've got it wrong again i mean a single oxygen atom ion thingymajig, not combined with another oxygen atom)

[CaptainPanic]

If you would somehow have only water and a single oxygen atom, then you might get peroxide as a result.

 

But it's quite unlikely that you will get a single oxygen atom in the presence of only water... and a single oxygen atom would much rather react with something other than the water.

[Horza2002]

Reacting the oxygen dianionn O^2-, with water will give you two moles of hydroxide. The oxygen dianion is the conjugate base of hydroixde (i.e. what you get if you were to deprotonate hydroxide). Obviously, this is very hard to do and so the oxygen dianion simply deprotonates water so fast it doesn't have chance to do anything else:

 

O^2- + H₂O ==> 2 HO^-

 

So, no, it won't give you hydrogen peroxide

[the guy]

so do you get in the end then?

[mississippichem]

so do you get in the end then?

 

I think you might be more likely to get hydrogen peroxide if the oxygen species was a peroxide ion [ce]O_{2}^{2-}[/ce], not totally sure though.

 

Combining and oxide ion, [ce]O^{2-}[/ce], with water to give hydrogen peroxide though; that reaction has a very positive Gibbs energy, making it extremely unfavorable. I'm saying the same thing Horza2002 said but from a thermodynamic standpoint rather than kinetic.

Edited March 15, 2011 by mississippichem

[Horza2002]

If you started with the peroxide dianion, then you would get hydrogen peroxide in water; it would deprotontate the water in the same way as the oxide anion would. But seeing _{the guy} seems to be asking about forming O-O bonds, then its not useful.

[mississippichem]

If you started with the peroxide dianion, then you would get hydrogen peroxide in water; it would deprotontate the water in the same way as the oxide anion would. But seeing _{the guy} seems to be asking about forming O-O bonds, then its not useful.

 

True, i guess what I said was true but not useful. Peroxides are not a good starting material to make peroxides .

[Pwyll Pendefig Dyfed]

would atomic oxygen react with a water molecule, on contact, to give hydrogen peroxide?

(if i've got it wrong again i mean a single oxygen atom ion thingymajig, not combined with another oxygen atom)

 

At normal temperature and pressure it's going to go the other way:

 

H₂O₂ -> H₂O + O₂

The question is whether it is an equilibrium reaction, so can uthe equilibrium be shifted the other way by changing the temperature and/or pressure (using Le Chateliers principle)

[mississippichem]

At normal temperature and pressure it's going to go the other way:

 

H₂O₂ -> H₂O + O₂

The question is whether it is an equilibrium reaction, so can uthe equilibrium be shifted the other way by changing the temperature and/or pressure (using Le Chateliers principle)

 

Though it could be, I doubt this is a equilibrium process, in practice anyway. There is a large electrochemical potential difference between water and hydrogen peroxide. This is also a radical reaction which is one more reason to suggest this is not an equilibrium process. Not to say that radical reactions are not reversible, many of the nitrogen oxides undergo radical equilibrium reactions that are heat controlled. So microscopic reversibility still applies here, but homolytic bond dissociation energies tend to be high and have large kinetic barriers.

[John Cuthber]

I'm not sure the question is really clear enough to answer.

 

The question doesn't just ask about the reaction of ions with water; it asks specifically about the reaction of oxygen atoms with water.

(atomic oxygen + water molecule = hydrogen peroxide? )

 

Under equilibrium conditions at NTP, oxygen atoms don't exist so I don't think the eqm position of the reaction matters.

 

If you got a stream of oxygen put it through an arc or zapped it with hard UV and thereby generated some atoms then passed the gas mixture rapidly into water so that not all the atoms recombined before they got to the water then I'm ready to bet that some H2O2 would be formed.

[Horza2002]

John, I know the question was about oxygen atoms....but as you said, its extremely difficult to actually get oxygen atoms. I've just searched for water oxidation by oxygen with Web of Knowledge and there doesn't seem to be any papers on using oxygen atoms. However, there was over 10,000 results from my search so I didn't go through them all.