Phosphorus Trichloride - PCl3

What is Phosphorus Trichloride?

Phosphorus trichloride is a fuming liquid with the formula PCl3.Phosphorus trichloride is a colourless transparent motile liquid. It is the most important phosphorus halide.

Phosphorus trichloride (PCl3) is manufactured by burning molten white phosphorus in dry chlorine. An explosion occurs when phosphorus trichloride is brought in contact with nitric or nitrous acid. A phosphorus trichloride produces acute systemic effects by absorption through the skin into the bloodstream.

Other names – Trichlorophosphine, Phosphorus trichloride, Phosphorus chloride


Phosphorus Trichloride


1.57 g/cm³

Molecular Weight/ Molar Mass

137.33 g/mol

Boiling Point

76.1 °C

Melting Point

-93.6 °C

Chemical Formula


Table of Contents

Phosphorus Trichloride Structure – PCl3

Phosphorus Trichloride Structure

Physical Properties of Phosphorus Trichloride – PCl3


Pungent and irritating odour


Yellow fuming liquid

Covalently-Bonded Unit


Molecular Geometry

Trigonal Pyramidal




Soluble in water

Chemical Properties of Phosphorus Trichloride – PCl3

  • Phosphorus trichloride on further chlorination forms Phosphorus pentachloride. The chemical reaction is given below.

PCl3 + Cl2 → PCl5

  • Phosphorus trichloride dissolves in water and forms phosphoric acid and hydrogen chloride. The chemical reaction is given below.

PCl3 + 3H2O → H3PO3 + 3HCl

Uses of Phosphorus Trichloride – PCl3

  • The Largest use for phosphorus trichloride is for making phosphorus oxychloride by oxidising it with oxygen.
  • Used as an important intermediate in the production of phosphate ester insecticides.
  • Used as a chlorinating agent for converting alkyl alcohols to alkyl chlorides and organic acids to organic acid chlorides and also as a catalyst.
  • Used in the production of important compounds like phosphorous pentachloride, phosphoryl chloride, thiophosphoryl chloride, pseudohalogens and phosphonic acids.
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