Phosphorus Trichloride(PCl3) Properties(25 Facts)

Phosphorus trichloride is an inorganic compound with strong odour. Let us explore it in detail in this article.

Phosphorus trichloride consists of central atom Phosphorus and three surrounding chlorine atoms. It is prepared by the reaction between chlorine and white phosphorus. It has a standard enthalpy of formation of -319.7 kJ/mol. It has a trigonal pyramidal shape.

Let us discuss Chemical classification, CAS number, ChemSpider ID, molar mass, viscosity and other important properties in this article.

Phosphorus trichloride IUPAC name

The IUPAC name of PCl3 is Trichlorophosphane.

Phosphorus trichloride chemical formula

The chemical formula of Phosphorus trichloride is PCl3.

Phosphorus trichloride CAS number

The CAS Phosphorus trichloride is 7719-12-2.

Phosphorus trichloride ChemSpider ID

The ChemSpider ID of PCl3 is 22798.

Phosphorus trichloride chemical classification

The chemical classification of PCl3 is as follows-

  • PCl3 is an inorganic compound.
  • It has a chemical formula PCl3.
  • It is a phosphorus halide with one P and three Cl atoms.
  • It is a covalent compound with bond length 204 pm.                  
phosphorus trichloride properties
Phosphorus trichloride

Phosphorus trichloride molar mass

PCl3 has a molar mass of 137.33 g/mol.

Phosphorus trichloride color

The PCl3 is colourless (when pure) or sometimes yellow liquid.

Phosphorus trichloride viscosity

The viscosity PCl3 is 0.65 cP at 0οC and 0.438 cP at 50οC.

Phosphorus trichloride molar density

The molar density of PCl3 is 1.574 g/cm3.

Phosphorus trichloride melting point

The melting point of PCl3 is -93.6οC or 179.6 K.

Phosphorus trichloride boiling point

The boiling point of PCl3 is 76.1οC or 349.2 K

Phosphorus trichloride state at room temperature

PCl3 exists as colourless or a yellow oily liquid at room temperature.

Phosphorus trichloride ionic/covalent bond

PCl3 consists of three covalent bonds. As both P and Cl are non-metals, they do not have tendency to donate electrons. Thus, P and Cl forms covalent bonds.

Phosphorus trichloride covalent radius

In PCl3, P atom has a covalent radius of 106 pm while Cl has covalent radius of 99 pm.

Phosphorus trichloride electron configurations

The electronic configuration of P is [Ne] 3s2 3p3. The electronic configuration of Cl is [Ne] 3s2 3p5.

Phosphorus trichloride oxidation states

In PCl3, the oxidation state of P is +3 while the oxidation state of Cl is -1.

Phosphorus trichloride acidity/alkaline

PCl3 is a Lewis base (alkaline) because the central atom P has a lone pair of electrons which it can donate to a Lewis acid.

Is Phosphorus trichloride odourless?

PCl3 has a pungent odour like HCl.

Is Phosphorus trichloride paramagnetic?

A diamagnetic substance contains no unpaired electrons while a paramagnetic substance contains unpaired electrons.

PCl3 is diamagnetic in nature because it does not contain unpaired electrons.

Phosphorus trichloride hydrates

PCl3 undergoes hydrolysis with water to form phosphorous acid and hydrochloric acid.

PCl3 + 3H2O –>H3PO3 + 3HCl

Phosphorus trichloride crystal structure

In PCl3, the central atom P is sp3 hybridized so the crystal structure of PCl3 is trigonal pyramidal with a bond angle of 103ο.

Phosphorus trichloride polarity and conductivity

  • PCl3 is polar molecule because high electronegativity of Cl atoms than P, pull electrons of the centre P atom. It has a dipole moment of 0.97 D.
  • PCl3 does not conduct electricity because no ions or no mobile electrons are available to carry current.

Phosphorus trichloride reaction with acid

PCl3 reacts with organic acid like CH3COOH to form acyl chloride (CH3COCl) and H3PO3.

CH3COOH + PCl3 –> CH3COCl + H3PO3

Phosphorus trichloride reaction with base

PCl3 reacts with ethanol in the presence of base R3N (tertiary amine).

POCl3 + 3 EtOH + 3 R3N –> P(OEt)3 + 3 R3NH+Cl

Phosphorus trichloride reaction with oxide

PCl3 reacts with sulphur trioxide to form Phosphorus Oxychloride (POCl3) and sulfur dioxide(SO2).

PCl3 + SO3 –> POCl3 + SO2

Phosphorus trichloride reaction with metal

PCl3 is used to electrodeposit metal on the rubber.


PCl3 is a covalent compound consisting of three covalent bonds. It is a diamagnetic in nature. It exists as liquid at room temperature.