Phosphorus Pentachloride(PCl5) Properties(25 Facts)

Phosphorus Pentachloride is a halide compound formed with phosphorous with stability greater than other halides with P. Let us discuss more facts below.

Phosphorus Pentachloride is used as a chlorinating agent. It is found in the solid state ranging between transparent nature to yellow colored crystals. It has a high heat capacity of nearly 111 J mol-1 K-1.  It is hazardous to work with as it reacts violently with water and is corrosive in nature.

Phosphorus Pentachloride can be prepared by passing chlorine gas to PCl3 in a chamber. Let us learn more facts like IUPAC name, density and atomic mass below.

PCl5 IUPAC name

The IUPAC name of PCl5 is Phosphorous Pentachloride. Pentachloride stands for the five chlorine atoms connected to the central atom, phosphorous.

PCl5 chemical formula

The chemical formula of PCl5 (Phosphorous Pentachloride) is PCl5. The chemical formula suggests the molecule has five chlorine atoms with phosphorous as the central atom.

pcl5 logo
Trigonal pyramidal structure of PCl5

PCl5 CAS number

The CAS number of PCl5 is 10026-13-8.

PCl5 ChemSpider ID

The ChemSpider ID of PCl5 is 23204.

PCl5 chemical classification

The chemical classification of PCl5 are provided below.

  • PCl5 is a chlorinating agent.
  • PCl5 is present in the form of yellowish white crystals.
  • PCl5 is non-flammable in nature.
  • PCl5 is soluble in water partially.
  • PCl5 nearly soluble in non polar solvents like benzene, chlorocarbons etc.

PCl5 molar mass

The molar mass of PCl5 is 208.22 g/mol.

PCl5 color

The color of PCl5 is yellow with a tint of white. The color is due to the excitation of electrons when light falls on the molecule’s surface.

PCl5 viscosity

The viscosity of PCl5 has not yet been found fully due to a lack of studies done on it.

PCl5 molar density

The molar density of PCl5 is 2.1 g cm-3. It is the arrangement of all the atoms packed together in 1 cm3 volume.

PCl5 melting point

The melting point of PCl5 is 161 oC / 321 oF / 433.6 K. It has a high melting point than PF5.

PCl5 boiling point

The boiling point of PCl5 is 167 oC / 332 oF / 440 K. This amount of heat is required to undergo a phase transformation from liquid to vapor state.

PCl5 state at room temperature

The state of PCl5 at room temperature is solid. It is found in the form of crystals in yellow or white colors.

PCl5 covalent bond

PCl5 has covalent bonds present in it. All five bonds with two as the axial bonds and here as the equatorial bonds have covalent character as the electronegativity difference between P and Cl is less than 1.5.

PCl5 covalent radius

PCl5 covalent radius is estimated to be around 110 pm . P has 110 pm and Cl as 101 pm as the covalent radius.

PCl5 electron configurations

The electronic configuration of the overall molecule cannot be summed up but the individual atomic configurations can be written down as shown below.

The electronic configuration of P is 1s22s22p63s23p3 and of Cl is 1s22s22p63s23p5. Upon excitation of electrons in P, it has 1s22s22p63s13p33d1 configuration, and the five unpaired electrons in 3s, 3p and 3d form five sigma bonds with five Cl atoms.

PCl5 oxidation state

The oxidation state of the overall molecule is zero as the cation and anions balances each other. The oxidation state of P is +5 due to its expanded octet and the oxidation state of Cl is -1 as it requires only one electron to fills its outer shell configuration.

PCl5 acidity

PCl5 is a lewis acid showing acidity or acidic character. It can react with lewis bases like NH3 to form adducts.

  • PCl5 + NH3 -> Cl5P<-:NH3

Is PCl5 odorless?

PCl5 is not odorless as it has a very unpleasant dirty smell owing to the present of halogen atom.

Is PCl5 paramagnetic?

Paramagnetism is a phenomenon shown by materials that can attract magnetic field towards it without repelling it in opposite direction. Let us check if PCl5 is paramagnetic or not.

PCl5 is not a paramagnetic material as all the electrons in its outer orbits are used in forming five sigma bonds with five Cl atoms. As such no unpaired electron is left in the orbitals to attract the external magnetic field when it is applied.

PCl5 hydrates

PCl5 does not form hydrates as it does not have any extensive electronegative atoms like F, N or O to form H-bonding. However, it does react with water molecules to undergo hydrolysis to form phosphorus oxychloride.

  • PCl5 + H2O -> POCl3 + 2HCl

PCl5 crystal structure

The crystal structure of PCl5 is tetragonal with lattice parameters ( sides and angles ) as a = b ≠ c and α = β = γ = 90o.

PCl5 polarity and conductivity

  • The polarity of PCl5 is 0.
  • The PCl5 molecule has equivalent bonds.
  • The bond dipole vectors cancel each other in PCl5.
  • The conductivity of PCl5 is 1.21 * 10-3 S cm-1.

PCl5 reaction with acid

PCl5 is a lewis acid so it does not react with an acid generally. It can only react with bases.

PCl5 reaction with base

PCl5 reacts with base due to itself being a lewis acid with a tendency to accept electrons from lewis bases. An example is shown below.

  • PCl5 + NH3 -> Cl5P<-:NH3 ( An adduct )

PCl5 reaction with oxide

PCl5 reacts with oxides to form phosphorous oxychloride. An example is listed below.

  • PCl5 + SO2 -> POCl3 + SOCl2

PCl5 reaction with metal

PCl5 reacts with metals and tends to be corrosive toward it. The following examples are listed below.

  • 2PCl5 + Ag -> 2AgCl + PCl3
  • Sn +2PCl5 -> SnCl4 + 2PCl3


PCl5 is a highly hazardous material that reacts exothermically with water. It is used as a chlorinating agent. It reacts with bases, metals and oxides.