Question

Classify each molecule as polar or nonpolar. 

CHCl3 =

CH3OCH3 = 

BH3 = 

CH3CH2CH3 =

Answer 1

Condition to be polar or non-polar.

(To be molecule non-polar cetral atom must be combined with same type of element and cental atom must not contain lone pais of electron, then structure of the molecule will be symmetrical and dipole moment of the molecule will be zero)

(To be polar if atom attached with central atom are not same and /or cental atom contain lone pair of electron its structure become unsymmetrical and dipole momment become more than zero and molecule become polar. )

Answer (a)

CHCl₃ is a polar molecule because in the CHCl₃ molecule, there are three C-H which is non polar and one C-Cl.

C-Cl bond is polar due to electronegativity difference between Corban and Chlorine. Hence Dipole moment of the molecule become more than zero and it becomes polar.

Answer (b)  CH₃-O-CH₃ is polar. Though it might seem that it is non polar because dipole moment will be cancelled due to symmetry but actully it has no symmetry (iIn this molecule central atom is oxygen and attaced with corbon but oxygen contai lone pair of electron and it has no symmetry.and become polar.)

Explanation.

1. It has got tetrahedral geometry and 2 lone pairs sa a angular shape.

2. A dipole moment of molecule become more than zero and because of angular shape it is not cancelled.

Answer (c) BH₃ is non-polar.

Explanation. Each B-H bond is polar and forms a dipole because the B and H atoms have different elelectronegitivitys. The shape is trogonal planar which is symmetrical, so the dipoles /bond po;arities cancel. the resulting BH₃ molecule is non-polar.

Answer (d). CH₃CH₂CH₃ is non polar.

Explanation.: It is non-polar. the reason been that the electronegativity of the hydrogen around the cetral atom cancel out because they are well distrributed around it and corban have no lone pair of electron so structure of molecule has symmetry and dipole moment become zero.