S and H2O Reaction 1

[bonzoboy]

Will Steam (H2O) and sulfur react to produce H2S and Oxygen? Anybody have a chart showing the reaction chemistry at different temperatures?

 

[kenvlach]

No. Consider the Gibbs free energy at 25^oC of the reaction
H₂O(g) + S(s) = H₂S(g) + 1/2 O₂(g)

[Δ]G_{Rxn, 298 K} = -33.4 - (-228.6) kJ/mole
= +195.2 kJ/mole

But, you can burn H₂S(g) with O₂ to form SO₂ + H₂O which forms sulfurous acid H₂SO₃ which can be oxidized to sulfuric acid, H₂SO₄.

 

[bonzoboy]

Thanks for the response. I think part of my confusion is coming from the use of an equilbrium code that shows H2S and O2 as equilbrium products at 300 K. When I did a hand calc, like you showed, I get your answer. Now I'm perplexed why I'm getting O2 and H2S as products (from this spreadsheet code)

 

[25362]

In presence of an alkali to remove H2S, it appears that steam at high pressures can reduce sulfur.
See

http://www.iapws.jp/Proceedings/Symposium05/365Lin.pdf

 

[kenvlach]

25362,
Thanks for the link. But, sulfate forms, not O₂.

In the Frasch process, steam is pumped into underground deposits in order to extract liquid elemental sulfur.

H₂S hardly reacts with hot water under usual conditions:
H2S in hot water even with chlorination system
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