KH2PO4 - Monopotassium Phosphate

What is Monopotassium Phosphate?

Monopotassium Phosphate is the monopotassium salt of phosphoric acid with the formula KH2PO4. It is freely soluble in water and insoluble in ethanol. Commercially available as pure KH2PO4, when reacted with MgO, produces high-quality ceramics. It is formed by the chloride or potassium carbonate reaction with phosphoric acid, and the phosphate is derived in a pure form as a crystalline material.

Table of Contents

Monopotassium phosphate is prepared industrially by adding 1 mol of a water solution of potassium hydroxide to 1 mol of phosphoric acid.

Other names – Potassium dihydrogen phosphate, Potassium phosphate monobasic, Potassium phosphate monobasic

KH2PO4 Monopotassium Phosphate
Density 2.34 g/cm³
Molecular Weight/ Molar Mass 136.086 g/mol
Boiling Point 400 °C
Melting Point 252.6 °C
Chemical Formula KH2PO4

Monopotassium Phosphate Structure – KH2PO4

Monopotassium Phosphate Structure

Physical Properties of Monopotassium Phosphate – KH2PO4

Odour No odour
Appearance White powder, deliquescent
Covalently-Bonded Unit 2
Heavy Atom Count 6
Complexity 61.2
Solubility Soluble in water

Chemical Properties of Monopotassium Phosphate – KH2PO4

    • Monopotassium Phosphate dissolves in water forms phosphoric acid and potassium hydroxide. The chemical equation is given below.

KH2PO4 + H2O → H3PO4 + KOH

    • Monopotassium Phosphate reacts with a base like sodium hydroxide forms disodium phosphate, water and potassium hydroxide.

KH2PO4 + 2NaOH → H2O + KOH + Na2HPO4

Uses of Monopotassium Phosphate – KH2PO4

  • Used as a fertilizer because it contains potassium and phosphate that can be applied to both the soil and foliage.
  • Used in the manufacture of sodium phosphates, ammonium phosphates, calcium phosphates and other phosphates.
  • For colour preservation, it is used in eggs and is also used in low-sodium products, meat products and milk products.
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