How is PCl₃F₂ Non polar and PCl₂F₃ Polar ?

Please explain.

Dear student,

 

Both the compounds PCl₃F₂  and PCl₂F₃  have trigonal bipyramidal structure. But the difference is that in PCl₃F₂  , chlorine atoms are present on the equatorial bonds which cancel each others dipole moment and the two fluorine atoms are present on the axial bonds which also cancel each others dipole moment. So, the overall dipole moment of the molecule is zero. Therefore, it is non- polar.

While in PCl₂F₃ , two chlorine atoms and one fluorine atom are present on the eq. bonds so there exists some dipole moment in the molecule and the two fluorine atoms are present on the axial bonds. So, this molecule is polar.

 

Chemistry Consultant

Askiitians