4 H₃BO₃ (aq) + 2 NaOH (aq) → Na₂B₄O₇ (aq) + 7 H₂O (l)

This is an acid-base reaction (neutralization): H₃BO₃ is an acid, NaOH is a base.

Reactants:

• H₃BO₃ – Boric acid , Trihydrooxidoboron
  • Other names: Orthoboric acid , Boracic acid , Sassolite ... show moreOptibor , Borofax , Trihydroxyborane , Boron(III) hydroxide , Boron Trihydroxide , O-boric acid , Hydrogen borate show less
  • Appearance: White crystalline solid ; Odourless colourless crystals or white powder
• 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:

• Na₂B₄O₇ – Sodium tetraborate decahydrate
  • Other names: Borax , Borax decahydrate , Disodium tetraborate ... show moreSodium tetraborate , Borates, tetra, sodium salts (Anhydrous) , Disodium tetraborate, anhydrous , Sodium borate anhydrous , Anhydrous borax , Boric acid, disodium salt , Sodium biborate , Sodium pyroborate , Boron sodium oxide , Fused borax , Borax dehydrated , Disodium salt of boric acid , Sodium borate (anhydrous) show less
  • Appearance: White solid ; Colourless-to-white hygroscopic crystals or powder. turns opaque on exposure to air ; White to gray, odorless powder. [herbicide] [Note: Becomes opaque on exposure to air.]
• 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