P₂O₅ + 2 NaOH + H₂O → 2 NaH₂PO₄

This is an acid-base reaction (neutralization): P₂O₅ is an acid, NaOH is a base.

Reactants:

• P₂O₅
  • Names: Phosphorus pentoxide , Diphosphorus pentoxide , Phosphorus(V) oxide ... show morePhosphoric anhydride , Tetraphosphorus decaoxide , Tetraphosphorus decoxide , Phosphorus pentaoxide show less
  • Appearance: White powder | very deliquescent | odorless ; Hygroscopic white crystals or 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).
• 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

Products:

• NaH₂PO₄ – Sodium dihydrogen phosphate
  • Other names: Monosodium phosphate , Monobasic sodium phosphate; , Sodium dihydrogen phosphate; ... show moreSodium biphosphate , Anhydrous monobasic sodium phosphate , Phosphoric acid, monosodium salt , Sodium phosphate, monobasic , NaH2PO4 , Sodium phosphate monobasic anhydrous , E339i , E339(i) show less
  • Appearance: White powder or crystals