Name: Types of Intermolecular Forces
Uploaded: 2019-07-19
Duration: 8 min 7 s
Description: An intermolecular force mediates the interaction between molecules, including the forces of attraction or repulsion, which act between atoms and molecules.

Question

In certain polar solvent,

{PCl}_{5}

undergoes an ionisation reaction, in which

{Cl}^{-}

ion leaves one

{PCl}_{5}

molecule and attaches itself to another.

2 {PCl}_{5} ⇌ {PCl}_{4}^{+} + {PCl}_{6}^{-}

What are the changes in the geometrical shapes that occur in this ionisation?

Accepted Answer

$x$ -rays studies have revealed that solid ${PCl}_{5}$ consists of ionic lattices, tetrahedral ${[{PCl}_{4}]}^{+}$ cations and octahedral ${[{PCl}_{6}]}^{-}$ anions.

For ${PCl}_{5}$ :

Total number of the electron pairs $= \frac{5 + 35}{2} = 20$

Number of the bonded electron pairs $= 5$

Number of electron pairs around the central atom $= 20 - 15$

Number of the lone pair $= 0$

VSEPR notation $= {AX}_{5}$

$X =$ $\frac{1}{2}$ [Number of the valence electrons of the central atom] $+$ [Number of monovalent atoms group surrounding the central atom] $-$ [Charge on the cation, if the given species is a polyatomic cation] $+$ [Charge on the anion, if the given species is a polyatomic anion]

$X = \frac{1}{2} [5 + 5] - 0 + 0 = 5 ({sp}^{3} d)$ (Trigonal bipyramidal)

For ${PCl}_{4}^{+}$ :

Total number of the electron pairs $= \frac{5 + 28 - 1}{2} = 16$

Number of the bonded electron pairs $= 4$

Number of the electron pairs around the central atom $= 16 - 12 = 4$

Number of the lone pair $= 0$

VSEPR notation $= {AX}_{4}$

$X = \frac{1}{2} [5 + 4 - 1 + 0] = 4 ({sp}^{3})$ (Tetrahedral)

For ${PCl}_{6}^{-}$ :

Total number of the electron pairs $= \frac{5 + 42 + 1}{2} = 24$

Number of the bonded electron pairs $= 6$

Number of the electron pairs around the central atom $= 24 - 18 = 6$

Number of the lone pair $= 0$

VSEPR notation $= {AX}_{6}$

$X = \frac{1}{2} [5 + 6 - 0 + 1] = 6 ({sp}^{3} d^{2})$ (octahedral)

${PCl}_{5}$ has different axial and equatorial bond length and therefore, has an unsymmetrical structure, which is not stable. By dissociation, it changes into tetrahedral ${[{PCl}_{4}]}^{+}$ and octahedral ${[{PCl}_{6}]}^{-}$ , which are stable.

In certain polar solvent, ${PCl}_{5}$ undergoes an ionisation reaction, in which ${Cl}^{-}$ ion leaves one ${PCl}_{5}$ molecule and attaches itself to another. $2 {PCl}_{5} ⇌ {PCl}_{4}^{+} + {PCl}_{6}^{-}$
What are the changes in the geometrical shapes that occur in this ionisation?

Important Questions on Chemical Bonding and Molecular Structure

Learn and Prepare for any exam you want !

In certain polar solvent, PCl5 undergoes an ionisation reaction, in which Cl-ion leaves one PCl5 molecule and attaches itself to another. 2PCl5⇌PCl4++PCl6- What are the changes in the geometrical shapes that occur in this ionisation?

Important Questions on Chemical Bonding and Molecular Structure

Learn and Prepare for any exam you want !

In certain polar solvent, ${PCl}_{5}$ undergoes an ionisation reaction, in which ${Cl}^{-}$ ion leaves one ${PCl}_{5}$ molecule and attaches itself to another. $2 {PCl}_{5} ⇌ {PCl}_{4}^{+} + {PCl}_{6}^{-}$
What are the changes in the geometrical shapes that occur in this ionisation?