HCHO + 2 CuSO₄ + 4 NaOH → HCOOH + Cu₂O + 2 Na₂SO₄ + 2 H₂O

This is an oxidation-reduction (redox) reaction:

CuSO₄ is an oxidizing agent, HCHO is a reducing agent.

Reactants:

• HCHO – Formaldehyde , Methanal
  • Other names: Methyl aldehyde , Methylene glycol , Methylene oxide ... show moreFormalin (aqueous solution) , Formol , Carbonyl hydride , Formaldehyde (37% solution, methanol free) , FORMALDEHYDE , Formic aldehyde , Formaline , Fannoform , Chlodithane , Formalith , Methaldehyde , Formalina , Chlodithan , Aldeide formica , Paraform , Oxomethylene , Formalin , Formaldehyde solution , Oxymethylene , Oxomethane , Paraformaldehyde show less
  • Appearance: Colorless gas ; Colourless gas with pungent odour ; Colourless liquid with pungent odour ; Nearly colorless gas with a pungent, suffocating odor. [Note: Often used in an aqueous solution (see specific listing for Formalin).]
• CuSO₄ – Copper(II) sulfate
  • Other names: Cupric sulphate , Blue vitriol (pentahydrate) , Bluestone (pentahydrate) ... show moreBonattite (trihydrate mineral) , Boothite (heptahydrate mineral) , Chalcanthite (pentahydrate mineral) , Chalcocyanite (mineral) , Cupric sulfate , Copper sulfate (anhydrous) , CuSO4 , Copper sulfate , Cupric sulfate anhydrous , Copper monosulphate , Copper sulfate (1:1) , Cupric sulphate anhydrous , Copper sulphate , Copper(2+) sulfate , Copper(II) sulphate , Copper monosulfate , Cupric sulfate, anhydrous , Cupric sulphate, anhydrous , Sulfuric acid, copper(2+) salt(1:1) show less
  • Appearance: Gray-white (anhydrous) | blue (pentahydrate) ; White hygroscopic crystals
• NaOH
  • Names: Sodium hydroxide , Caustic soda , Lye ... show moreSoda lye , Sodium hydrate , NaOH , White caustic , Lye [Sodium hydroxide] show less
  • Appearance: White, waxy, opaque crystals ; White hygroscopic solid in various forms ; Colorless to white, odorless solid (flakes, beads, granular form).

Products:

• HCOOH – Formic acid , Methanoic acid
  • Other names: Carbonous acid; Formylic acid; Hydrogen carboxylic acid; Hydroxy(oxo)methane; Metacarbonoic acid; Oxocarbinic acid; Oxomethanol , Hydrogen carboxylic acid , Aminic acid ... show moreFormate , Formylic acid , Methoic acid , HCOOH , H-COOH , HCO2H , Bilorin , Sodium Formate , Formylate , Wonderbond Hardener M 600L , Methanoic acid monomer , Collo-Didax , Methanoate , Aminate , Add-F , Collo-Bueglatt , Sybest , Formira , Ameisensaure , Formisoton , Myrmicyl , Formic acid (85-95% in aqueous solution) show less
  • Appearance: Colorless fuming liquid ; Colourless fuming liquid with pungent odour ; Colorless liquid with a pungent, penetrating odor. [Note: Often used in an aqueous solution.]
• Cu₂O – Copper(I) oxide
  • Other names: Cuprous oxide , Dicopper oxide , Cuprite ... show moreRed copper oxide , Copper (i) oxide , Copper (I) oxide show less
  • Appearance: Brownish-red solid ; Yellow, red or brown crystalline powder
• Na₂SO₄
  • Names: Sodium sulfate , Sodium sulphate , Sulfate of sodium ... show moreThenardite (mineral) , Glauber's salt (decahydrate) , Sal mirabilis (decahydrate) , Mirabilite (decahydrate mineral) , Disodium sulfate , Anhydrous sodium sulfate , Sodium sulfate anhydrous , Sodium sulfate, anhydrous , Sodium sulphate anhydrous , Sodium sulphate, anhydrous , Sulfuric acid disodium salt, anhydrous , Disodium sulphate , Salt cake , Na2SO4 , Sulfuric acid disodium salt show less
  • Appearance: White crystalline solid | hygroscopic ; White hygroscopic solid in various forms
• 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