2 FeCl₃ + H₂S → 2 FeCl₂ + S + 2 HCl

This is an oxidation-reduction (redox) reaction:

H₂S is a reducing agent, FeCl₃ is an oxidizing agent.

Reactants:

• FeCl₃ – Iron(III) chloride , Iron trichloride
  • Other names: {{ubl , Ferric chloride , Ferric chloride (anhydrous) ... show moreIron(3+);trichloride , Ferric;trichloride , [FeCl3] , FeCl3 , Iron chloride , Flores martis , Molysite show less
  • Appearance: Green-black by reflected light; purple-red by transmitted light; yellow solid as hexahydrate; brown as {{abbr|aq.|aqueous}} solution ; Black-to-brown hygroscopic crystals
• H₂S – Hydrogen sulfide
  • Other names: D , Ihydrogen monosulfide|Dihydrogen sulfide|Sewer gas|Sulfane|Sulfurated hydrogen|Sulfureted hydrogen|Sulfuretted hydrogen|Sulfur hydride|Hydrosulfuric acid|Hydrothionic acid|Thiohydroxic acid|Sulfhydric acid}} , Hydrosulfuric acid ... show moreSewer gas , Sulfuretted hydrogen , H2S , Hydrogen sulphide , [SH2] , Dihydrogen sulfide , Dihydrogen monosulfide , Hydrogen monosulfide , Sulfide , Zwavelwaterstof , Sulfur hydroxide , Siarkowodor , Idrogeno solforato , Dihydrogen disulfide , Hydrosulfurate , Sulfureted hydrogen , Sulfur hydride , Hepatate , Sour gas , Hepatic gas , Stink dAMP , Hepatic acid , Dihydrogen sulphide show less
  • Appearance: Colorless gas ; Colourless compressed liquefied gas with characteristic odour of rotten eggs ; Colorless gas with a strong odor of rotten eggs. [Note: Sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presence of H2S. Shipped as a liquefied compressed gas.]

Products:

• FeCl₂ – Iron(II) chloride , Iron dichloride
  • Other names: Ferrous chloride , Rokühnite , [FeCl3] , FeCl3
  • Appearance: Tan solid (anhydrous) | Pale green solid (di-tetrahydrate) ; White-to-light-green hygroscopic crystals
• S
  • Names: Sulfur , S , Sulphur ... show moreElement 16 , Flowers of sulfur , Flour sulfur , Brimstone show less
  • Appearance: Yellow solid in various forms
• HCl – Chlorane , Hydrogen chloride
  • Other names: Hydrochloric acid , M , Uriatic acid ... show moreHydronium chloride , Chlorhydric Acid , Hydrochloric acid gas , HCl , Anhydrous hydrogen chloride , Hydrochloric acid, anhydrous , Aqueous hydrogen chloride , [Note: Often used in an aqueous solution.] show less
  • Appearance: Colorless, transparent liquid, fumes in air if concentrated ; Colorless gas ; Colourless compressed liquefied gas with pungent odour ; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]