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

This is an oxidation-reduction (redox) reaction:

2S-II-12e-→2SIV(oxidation)

7SVI+14e-→7SIV(reduction)

2FeII-2e-→2FeIII(oxidation)

FeS is a reducing agent, H2SO4 is an oxidizing agent, FeS is a reducing agent.

Reactants:

• FeS
  • Names: Iron(II) sulfide , Iron sulfide , Ferrous sulfide ... show moreBlack iron sulfide , Protosulphuret of iron , Ferrous sulphide , Iron(II) sulphide show less
  • Appearance: Gray, sometimes in lumps or powder
• H2SO4 – Sulfuric acid
  • Other names: Oil of vitriol , Sulfuric acid, concentrated (> 51% and < 100%) , H2SO4 ... show moreSulphuric acid , Battery acid , Hydrogen sulfate , [SO2(OH)2] , [S(OH)2O2] , Sulfuric acid (aqueous) show less
  • Appearance: Clear, colorless liquid ; Odourless colourless oily hygroscopic liquid ; Colorless to dark-brown, oily, odorless liquid. [Note: Pure compound is a solid below 51°F. Often used in an aqueous solution.]

Products:

• SO2 – Sulfur dioxide
  • Other names: Sulfurous anhydride , Sulphur dioxide , Sulfurous acid anhydride ... show moreSulfurous oxide , Sulfur oxide , Sulphur dioxide , sulfur dioxide , SO2 , R-764 show less
  • Appearance: Colorless gas ; Colourless gas or compressed liquefied gas with pungent odour ; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.]
• Fe2(SO4)3 – Iron(III) sulfate
  • Other names: Ferric sulfate , Sulfuric acid , Iron(3+) salt (3:2) ... show moreDiiron tris(sulphate) , Iron tersulfate , Iron sesquisulfate , Iron persulfate , Ferric tersulfate , Ferric sesquisulfate , Ferric persulfate , Diiron trisulfate , Iron(III) sulfate(VI) , Ferric sulfate anhydrous show less
  • Appearance: Grayish-white crystals
• H2O – Water, oxidane
  • Other names: Water (H2O) , Hydrogen hydroxide (HH or HOH) , Hydrogen oxide ... show moreDihydrogen monoxide (DHMO) (systematic name) , Hydrogen monoxide , Dihydrogen oxide , Hydric acid , Hydrohydroxic acid , Hydroxic acid , Hydrol , Μ-oxido dihydrogen , Κ1-hydroxyl hydrogen(0) show less
  • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas