Question

Which of these molecules are polar? Check all that apply. PCl3 SO2 CO2 CH2Cl2

Answer 1

Concepts and reason

If the electronegativity of the two bonded atoms are different then the bond is polar. Although, some molecules contain polar bonds, the molecule may be non-polar. If the polarity of all the bonds present in the molecule are cancel each other then molecule is non-polar.

Fundamentals

If one atom is highly electronegative than the other atom in the bond, then the highly electronegative atom attracts the bonding pair of electrons more than its share. Hence, partial negative charge is developed on the highly electronegative atom and partial positive charge is developed on the less electronegative atom.

The structures of the molecules and the direction of the dipolemoment of the bonds are as follows:

The resultant vector of the all the dipolemoments of the molecules are as follows:

Hence, the polar molecules are ${\rm{PC}}{{\rm{l}}_3}{\rm{,}}\,\,{\rm{S}}{{\rm{O}}_2}\,\,{\rm{and}}\,\,{\rm{C}}{{\rm{H}}_2}{\rm{C}}{{\rm{l}}_2}$ .

Ans:

Thus the polar molecules are ${\rm{PC}}{{\rm{l}}_3}{\rm{,}}\,\,{\rm{S}}{{\rm{O}}_2}\,\,{\rm{and}}\,\,{\rm{C}}{{\rm{H}}_2}{\rm{C}}{{\rm{l}}_2}$ .

Answer 2

The polar molecules are PCl3 SO2 and CH2Cl2 .

PCl3 is trigonal pyramidal due to lone pair of electrons .

SO2 is Bent ( V shaped) molecule due to lone pair of sulfur atoms, and oxygen is more electronegative than Sulfur . hence SO2 is polar molecule.

Dichloromethane is polar because chlorine atom is highly electronegative and pulls the electron away from carbon.

Carbon dioxide is non-polar, though oxygen is highly electronegative than carbon , the C=O bond cancel each other's dipole moment , hence CO2 becomes non-polar molecule.