4 H₂SO₄ (aq) + 2 FeCl₂ (aq) → 2 H₂O (l) + 4 HCl (aq) + SO₂ (aq) + Fe₂(SO₄)₃ (s)

This is an oxidation-reduction (redox) reaction:

H₂SO₄ is an oxidizing agent, FeCl₂ is a reducing agent.

This is a precipitation reaction: Fe₂(SO₄)₃ is the formed precipitate.

Reactants:

• 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.]
• 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

Products:

• 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
• 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.]
• 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