# Thread: Question on Diatomic Oxygen/Reaction

1. ## Question on Diatomic Oxygen/Reaction

So since Oxygen is a Diatomic gas, how come the Chemical Equation to obtain H2O is H2 + O ---> H2O? Why isn't it H2 + O2 ---> H2O? I understand that the second equation is unbalanced and the product would be 2H2O, but that product isn't normal water anymore; it's something called "Heavy water".

Could someone explain to me why Oxygen is monoatomic in a basic/natural reaction even though it's meant to be diatomic (it's found diatomic in nature apparently)?

2. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
So since Oxygen is a Diatomic gas, how come the Chemical Equation to obtain H2O is H2 + O ---> H2O? Why isn't it H2 + O2 ---> H2O? I understand that the second equation is unbalanced and the product would be 2H2O, but that product isn't normal water anymore; it's something called "Heavy water".

Could someone explain to me why Oxygen is monoatomic in a basic/natural reaction even though it's meant to be diatomic (it's found diatomic in nature apparently)?
To be honest no one really knows how Earth got so much water to begin with (there are different theories like it came during the formation when heavy asteroids and comets filled with water and stuff stuck the Earth's surface, but there's no definitive answer). So practically now most of the water is just going through a recycling phase where it rains and there evaporates and the process repeats. As to ur question about the formation I don't think that second equation u gave is for heavy water (heavy water is when the hydrogen has an extra neutron, so the state of oxygen as a atom or molecule won't affect that)

3. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by jazz519
To be honest no one really knows how Earth got so much water to begin with (there are different theories like it came during the formation when heavy asteroids and comets filled with water and stuff stuck the Earth's surface, but there's no definitive answer). So practically now most of the water is just going through a recycling phase where it rains and there evaporates and the process repeats. As to ur question about the formation I don't think that second equation u gave is for heavy water (heavy water is when the hydrogen has an extra neutron, so the state of oxygen as a atom or molecule won't affect that)
But then how come the monoatomic/diatomic gas come into play? If Oxygen is found diatomic in nature, why is the formula H2 + O instead of H2 + O2? Oh and the heavy water thing came up was when I searched up 2H2O on Google and the Wikipedia page for "Heavy Water" was the first thing that came up.

4. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
But then how come the monoatomic/diatomic gas come into play? If Oxygen is found diatomic in nature, why is the formula H2 + O instead of H2 + O2? Oh and the heavy water thing came up was when I searched up H2O2 on Google and the Wikipedia page for "Heavy Water" was the first thing that came up.
It has to do with the electronegativity. H2O is more very much more stable than H2O2. Putting H2O2 into the sun decomposes it H2O and O2 (very little energy required

Also H2O2 is bleech, not heavy water.

5. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by dan964
It has to do with the electronegativity. H2O is more very much more stable than H2O2. Putting H2O2 into the sun decomposes it H2O and O2 (very little energy required

Also H2O2 is bleech, not heavy water.
Oh sorry, I meant 2H2O.

6. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
Oh sorry, I meant 2H2O.
compare the pair

2 lots of water: $2H_2O$ or $2\,H_2O$
vs.
1 lot of heavy water: $^2H_2O$

the problem is with Google. (Google does not do superscripts or subscripts)
if you look at the wikipedia article the 2 is superscripted.
https://en.wikipedia.org/wiki/Heavy_water

7. ## Question on Diatomic Oxygen/Reaction

Originally Posted by dan964
compare the pair

2 lots of water: $2H_2O$ or $2\,H_2O$
vs.
1 lot of heavy water: $^2H_2O$

the problem is with Google. (Google does not do superscripts or subscripts)
if you look at the wikipedia article the 2 is superscripted.
https://en.wikipedia.org/wiki/Heavy_water
I get it now thanks.

Also say we were trying to "create" water. Would we do H2 + O ---> H2O or would we do 2H2 + O2 ---> 2H2O? Since Oxygen is a Diatomic gas, wouldn't the second option make sense? You mentioned electronegativity, I understand that part; but don't get how in "nature" if Oxygen is found diatomically- how the H2 + O ---> H2O option comes up. It only makes sense to have 2H2 + O2 -->2H2O.

Also, you mentioned you can decompose Hydrogen Peroxide by adding sunlight, how does that work? How in an experiment would you decompose a compound for example? We learnt about decompositions, but don't think we did a decomposition reaction as a practical.

8. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
I get it now thanks.

Also say we were trying to "create" water. Would we do H2 + O ---> H2O or would we do 2H2 + O2 ---> 2H2O? Since Oxygen is a Diatomic gas, wouldn't the second option make sense? You mentioned electronegativity, I understand that part; but don't get how in "nature" if Oxygen is found diatomically- how the H2 + O ---> H2O option comes up. It only makes sense to have 2H2 + O2 -->2H2O.

Also, you mentioned you can decompose Hydrogen Peroxide by adding sunlight, how does that work? How in an experiment would you decompose a compound for example? We learnt about decompositions, but don't think we did a decomposition reaction as a practical.
We would do the second equation with oxygen gas, but that reaction is pretty dangerous as seen on YouTube videos when they light a hydrogen gas filled balloon with a flame to imitate the reaction, I doubt they would let students do it.

You can use like uv lamps or just use something like a magnifying glass to concentrate the sunlight on the compound

9. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by jazz519
We would do the second equation with oxygen gas, but that reaction is pretty dangerous as seen on YouTube videos when they light a hydrogen gas filled balloon with a flame to imitate the reaction, I doubt they would let students do it.

You can use like uv lamps or just use something like a magnifying glass to concentrate the sunlight on the compound
Ok, so in a nutshell; Oxygen doesn't necessarily have to be Diatomic in Chemical reactions even though they're found to be Diatomic in nature. Sometimes in a Chemical reaction it can be in a monoatomic form?

10. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
Ok, so in a nutshell; Oxygen doesn't necessarily have to be Diatomic in Chemical reactions even though they're found to be Diatomic in nature. Sometimes in a Chemical reaction it can be in a monoatomic form?
Yep, however its very rare for it to be in a monoatomic form in chemical reactions because it is actually a free radical in its atomic state, as it has 6 electrons in the valence shell, two being unpaired, making it unstable and very reactive.

11. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by jazz519
Yep, however its very rare for it to be in a monoatomic form in chemical reactions because it is actually a free radical in its atomic state, as it has 6 electrons in the valence shell, two being unpaired, making it unstable and very reactive.
So if we were hypothetically trying to "create" water by using H2 + O ---> H2O, would we be at risk of getting injured due to Oxygen being very reactive and unstable? Also, is there a difference between 2H2O and H2O (property wise)?

12. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
So if we were hypothetically trying to "create" water by using H2 + O ---> H2O, would we be at risk of getting injured due to Oxygen being very reactive and unstable? Also, is there a difference between 2H2O and H2O (property wise)?
Yep since its a gas it spreads out while in the air, so it could potentially react with ur DNA and strip away electrons from it, which can lead to mutations etc.

If you mean the heavy water and the normal water, here's a good table:https://imgur.com/iDHmLm1

13. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by jazz519
Yep since its a gas it spreads out while in the air, so it could potentially react with ur DNA and strip away electrons from it, which can lead to mutations etc.

If you mean the heavy water and the normal water, here's a good table:https://imgur.com/iDHmLm1
I meant just normal 2H2O (without superscript). There wouldn't be a difference from that and H2O would there? Also, what does the superscript for 2H2O mean (heavy water)?

14. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
I meant just normal 2H2O (without superscript). There wouldn't be a difference from that and H2O would there? Also, what does the superscript for 2H2O mean (heavy water)?
yeah the first bit no difference (no superscript is just a coefficient for the amount of water). The second one yeah the superscript means heavy water since later on you will see we write nucleus as like https://www.antonine-education.co.uk.../Fission_5.gif

where the top is the neutrons + protons and the bottom the protons (so the 2 on the heavy water is from 1 proton and 1 neutron)

15. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by jazz519
yeah the first bit no difference (no superscript is just a coefficient for the amount of water). The second one yeah the superscript means heavy water since later on you will see we write nucleus as like https://www.antonine-education.co.uk.../Fission_5.gif

where the top is the neutrons + protons and the bottom the protons (so the 2 on the heavy water is from 1 proton and 1 neutron)
Oh right, they're Isotopes. My bad. But does the superscript of 2 apply to just the Hydrogen? So that Heavy water would mean there's 2 of the same Hydrogen Isotopes mixed with regular Oxygen?

16. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
Oh right, they're Isotopes. My bad. But does the superscript of 2 apply to just the Hydrogen? So that Heavy water would mean there's Hydrogen Isotopes mixed with regular Oxygen?
Yeah only applies to the hydrogen. So yeah as you said its just practically a different isotope of hydrogen with normal oxygen.

17. ## Re: Question on Diatomic Oxygen/Reaction

You can also get variations in the oxygen isotopes too so I guess thats another type of heavier water too

18. ## Re: Question on Diatomic Oxygen/Reaction

Thanks. Also, if we were trying to 'create' Water and H2 + O ---> H2O wouldn't be safe; why do so many people come up with that equation instead of 2H2 + O2 ---> 2H2O? The second one makes much more sense since Oxygen is Diatomic (and stable) and it's not a 'risky' experiment if it were to be conducted.

19. ## Re: Question on Diatomic Oxygen/Reaction

Originally Posted by _Anonymous
Thanks. Also, if we were trying to 'create' Water and H2 + O ---> H2O wouldn't be safe; why do so many people come up with that equation instead of 2H2 + O2 ---> 2H2O? The second one makes much more sense since Oxygen is Diatomic (and stable) and it's not a 'risky' experiment if it were to be conducted.
Both of them are pretty dangerous to be fair. the first one a bit more because of the radicals, but the second one also because there is a massive flame that erupts after you initiate the reaction. In an exam though if they asked for a water formation equation the second one is better to do, also because on the standard potentials sheet the oxidation and reduction equations for water when u add the two it ends up as that equation

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