shipwreck question (1 Viewer)

[Steven12]

okay, i just want to know how to properly explain question. i get confused easily


the corrosion of shipwrecks is caused by the sulphate-reducing action by anaerobic bacteria.

so4+ 10H+ + 8e --> H2S +4H2O

now where does the hydrogen ions and electrons coming from?
in my textbook, it has H2O instead of H+ ions.

electrons are from the Iron from shipwreck right?

what oxidise the iron then?

and the sulphate reduces to hydrogen sulfide, and hydrogen sulfide is an acid and that promote acidic environment , which accelerate the corrosion(is that correct?, if not, where do the hydrogen ions originate?)

now rust needs hydroxide, how does that form?

arrr, can somebody answer this dot point comprehensively?

 

[Tommy_Lamp]

SRB produce the compound hydrogen sulfide H2S from the sulfate ions that are plentiful in sea water:
SO42– + 10H+ + 8e– --> H2S + 4H2O
Corrosion of metals produces metal ions,
e.g. Fe + 2H+ --> Fe2+ + H2
H2S, produced by the action of SRB is a weak acid that releases hydrogen ions and sulfide ions.
H2S 2H+ + S2–
The sulfide ions from the H2S can precipitate Fe2+ ions to form insoluble, black iron (II) sulfide FeS: Fe2+ + S2– --> FeS(s)
The presence of black FeS indicates that SRB are present.
The precipitation of FeS removes sulfide ions and encourages further ionisation of H2S releasing more H+.

 

[Steven12]

so the hydrogen ions came from dihydrogen sulfide. which is an weak acid,. and the hydrogens ions oxdise the metal.

so there is no iron hydroxide in this process since there is little oxygen.right?

how does the acidic environment promote corrosion?

 

[MaryTylerMoore]

The acid acts as an electrolyte and a catalyst, aiding corrosion.