Cu + S: predict gas product

[SaintJude]

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So this threads relates to those AAMC questions that ask you "Which gas likely evolved?" But I made this up myself.

So Cu + S --> What gas will form? H2 or H2S?

I think H2S gas will form instead of H2 gas, b/c the S is more electronegative than H

S(s) + 2 H+ + 2 e- --> H2S (g) Standard reducing potential = 0.14 vs. E of H = 0.

In fact, thinking about it now in terms of reducing potentials the only time H2 gas is likely to form is if water the primary reactant--b/c water is actually less likely to reduce than H2 gas.

Anyone want to agree or am I talking BS ?

 

[SaintJude]

But then I just don't understand how this reaction occur:

2 NaCl + 2 H2O → Cl2 + H2 + 2 NaOH

I would not have predicted these products....

 

[kasho11]

That's because that reaction requires electrolysis, Cl gets oxidized and H2O gets reduced, which would not occur naturally. Given the input of energy though, that reaction happens.

Also I can't think of any other products forming from that reaction, that seems to be the only actual "reaction" that could occur in water.