Question

Which of the following molecules are polar? XeCl2 COF2 PCl4F SF6 PCl3

Answer 1

Solution:

Following compounds are polar:

COF2 - COF2: C has four valence electrons uses two to bind the F atoms and two to bind O (satisfy the octet of O). The molecule is AX3 trigonal planar the C-F→ δ- vectors do not cancel (despite partial offset by O) so molecule is polar.

PCl4F- This is an AX5 system trigonal bipyramid with the F atom axial (you would not be expected to know but get same result if it goes equatorial). The P:F → δ- vector is not cancelled so the molecule is polar.

PCl3 - Chlorine is more elctronegative than phosphorus . P has a lone pair of electrons , every Cl atom has three pairs of electrons . The molecule is not symmetrical . Shared electrons tend to go nearer towards the chlorine side the chlorine atoms are shifted towards one side of the center of the molecule , and a net dipole effect is created So this molecule is polar .