[HSOoi]

Hi there,

Hydrogen and chlorine gas will burn to produce hydrogen chloride gas.

H₂ + Cl₂ 2HCl

What will happen if oxygen is present inside the reaction? Will water be formed?

H₂ + Cl₂ + O₂  ?

Is there any reactivity list for non-metals?

[magician4]

this question isn't as easily answered as it might seem from a first glance...

first of all, what you have here is a case of competing reactions, as both reactions (hence their products) might occur

to judge which of those might be more "powerfull", hence dominate the product range, sometimes it is interesting to discuss a situation, where one of the products already has formed , and let this "react" with the other component

what we'll find is, that

H₂O + Cl₂  no reaction
4 HCl + O₂  2 H₂O + 2 Cl₂

these findings would suggest that it's water (and not HCl) that is formed by the end of the day

furthermore , you might also make use of electrochemical series*⁾ and compare the redox behaviour (!) chlorine / chloride vs. oxygen / oxide
( H₂O = 2 H⁺ + O^2- ; HCl = H⁺ + Cl^- )
and find:
Cl^- + O₂  2 O^2- + 4 Cl₂

... i.e. more or less the same picture

so much for thermodynamical considerations at standard conditions

the problem however is, that if you ever saw oxygen/hydrogen reacting ( or, for that matter , chlorine / hydrogen) , you'd immediately knew that here we'd have anything but standard conditions, let alone "equilibrium of products " (which would be needed to apply classical thermodynamics at all)

what we'd have here would be a case of free radical reactions at varying temperature, pressure conditions instead, with a product range most probably ruled by kinetics: an explosion.
Now, kinetics under such conditions is "quite complicated" at least, and most difficult to calculate for.

For example, the kinetics of 4 HCl + O₂  2 H₂O + 2 Cl₂ at room temperature is that lame, that usually a mixture of HCl gas and oxygen would be quite stable over a long time (the reaction is "kinetically hindered").
[thats one of the reasons why hydrochloric acid in water is that stable with air contact ( and doesn't decay easily, producing chlorine gas thereby, which would be a real problem if we thought , for example , of the seas of the world)]
... but at elevated temperatures things might be ( and in this case: are) quite different , and product range control becomes somewhat casual: if by chance a HCl formed will "escape" the core of the explosion and cool down before meeting an oxygen, maybe nothing else will happen  (and the opposite: if a chlorine radical hits a water molecule at sufficient speed, the result might well be a HCl forming and a hydroxyl radical left behind)

however, even with this situation already being somewhat complicated, there's more to come:
- chlorine and oxygen might react, too, to form for example the (instable) ClO₂
- there's more than just one product for oxygen, hydrogen ( i.e there's also H₂O₂ , just to name one)
... and like a dozend further known intermediates and possible products for the reaction hydrogen, oxygen alone
... and some secondary reactions that might occur, like, for example, the well known (if only minor) solubility of chlorine in water ( Cl₂ + H₂O  ::equil::HCl + HOCl , just to name one of those)


So, to cut a long story short: from naive considerations , my expectation would be that we should find (mostly) water with (some) HCl in it and a lot of chlorine gas left behind, and a real zoo of trace products accompanying this , some of them more or less shortlived , and some of them giving secondary reactions with each other


hope this kind of answers your question?

regards

Ingo


*⁾
if you wish, you might consider this to be kind of a "reactivity list"