Sciencemadness Discussion Board - Which one is correct?

Which one is correct?

camurgo - 7-8-2019 at 06:35

Hi everyone.

On the subject of mixing FeS and H2SO4 I found resources describing two different equations:

a) FeS + H2SO4 → FeSO4 + H2S

b) FeS + H2SO4 → FeO + H2O + SO2

Which one is correct? Or, is it possible that both are correct depending how you mix the reagents?

Thank you.

[Edited on 7-8-2019 by camurgo]

Tsjerk - 7-8-2019 at 07:38

Sulfuric acid becomes oxidizing at higher temperatures, so I guess the second reaction happens at higher temperatures. I expect the Fe(II) to get oxidized to Fe(III) though.

icelake - 7-8-2019 at 07:41

The first one is definitely correct.

There is a missing S atom in your second equation, but it could be correct.

https://pubs.acs.org/doi/abs/10.1021/ie990717z

H₂S + H₂SO₄ → S + SO₂ + 2H₂O

[Edited on 7-8-2019 by icelake]

[Edited on 7-8-2019 by icelake]

camurgo - 7-8-2019 at 07:54

Thank you all. I didn't catch the missing S. And just now I found yet another one. The last one I promise:

2FeS + 10H2SO4 → Fe2(SO4)3 + 9SO2 + 10H2O

This one is balanced. Would you know if this is a possible actual reaction?

Thank you.

[Edited on 7-8-2019 by camurgo]

Tsjerk - 7-8-2019 at 08:22

Hmm, the products look fine, and it looks balanced... 2FeS is losing 2 x (1+6) electrons, sulfate is gaining 7 x 2 electrons.

AJKOER - 7-8-2019 at 12:38

Your current balanced the equation exercise has only partial resemblance to the 'actual' advanced chemistry. But if you want real, here is a related work 'Corrosion Mechanism of Nickel in Hot, Concentrated H2SO4' in Journal of The Electrochemical Society, 147 (10) 3637-3646 (2000) 3637 at http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.102...

The first presumed reaction is presented in reaction system [3]:

Anode: Ni --> Ni(2+) + 2 e-

Cathode: 4 H2SO4 + 2 e- --> SO4(2-) + SO2 + 2 HSO4- + 2 H3O(+) [3]

Total: Ni + 4 H2SO4 --> NiSO4 + SO2 + 2 HSO4- + 2 H3O(+)

which turns out to be an inaccurate rendition as, to quote, "composition of the various solid corrosion products demonstrates that other possible reduction products include sulfide ions and elemental sulfur."

The work proceeds on to depicted in Fig. 10 four mechanism detailed in reaction systems [8] to [14].

In the current context, one could substitute for Ni with Fe(2+) and for Ni(2+) with Fe(3+).

Interestingly, Eq [8] cites H2S formation and Eq[14] cites sulfur, so to answer your question "Would you know if this is a possible actual reaction?" the answer is yes, in part, but a bit too advanced to explain it simply, in my humble opinion.

Also a comment relating to a comparison between nickel and iron, to quote from the source:

"Since nickel has a similar response to anodic polarization in concentrated H2SO4 as does iron in its well-known sulfation stage [45,46], and forms a similar sulfate salt film, it is reasonable to postulate that nickel has a similar rate-determining step as does iron; the convective mass transfer of the metal cation from the saturated metal sulfate layer."
---------------------------------------

The good news is your 'teacher', I suspect, is not a real chemistry professional, and therefore, likely clueless on the real science, and what you are doing is a simple balance the equation game.

[Edited on 8-8-2019 by AJKOER]

camurgo - 9-8-2019 at 17:41

Thank you for the answer. I'll be trying to wrap my mind around this.

Sulaiman - 9-8-2019 at 18:52

@AJKOER

icelake - 9-8-2019 at 22:47

http://jes.ecsdl.org/content/147/10/3637.full.pdf+html

correct doi: doi: 10.1149/1.1393952