5 H2SO4 + 2 P → 2 H3PO4 + 5 SO2 + 2 H2O – Balanced equation

This is an oxidation-reduction (redox) reaction:

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

Reactants:

• H₂SO₄ – Sulfuric acid
  • Other names: Oil of vitriol , Sulfuric acid, concentrated (> 51% and , H2SO4
  • 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.]
• P

Products:

• H₃PO₄
  • Names: Phosphoric acid , Orthophosphoric acid , Phosphoric(V) acid
  • Appearance: Hygroscopic colourless crystals ; Thick, colorless, odorless, crystalline solid. [Note: Often used in an aqueous solution.]
• SO₂ – Sulfur dioxide
  • Other names: Sulfurous anhydride , Sulphur dioxide , Sulfurous acid anhydride
  • 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.]
• H₂O – Water, oxidane
  • Other names: Water (H2O) , Hydrogen hydroxide (HH or HOH) , Hydrogen oxide
  • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas