Question

The molecule having the largest dipole moment among the following is:
(A) $CH{{I}_{3}}$
(B) $C{{H}_{4}}$
(C) $CHC{{l}_{3}}$
(D) $CC{{l}_{4}}$

Answer 1

Hint: A dipole moment arises due to the electronegativity difference between the two atoms of a bond. Both the ionic and polar covalent bonds can have a dipole moment. It is a vector quantity having both magnitude and direction. The symbols used to represent the charges on the two elements are $\delta +$and$\delta -$, where more electronegative atoms get $\delta -$ charge and less electronegative atoms get $\delta +$ charge. The more electronegative atom pulls the shared pair of electrons towards itself.

Complete Step by Step Answer:
In chloroform ($CHC{{l}_{3}}$), the bond polarity in the $C-H$bond is from hydrogen to carbon, whereas in the $C-Cl$bond, the bond polarity is from carbon to chlorine. Therefore, the net dipole moment in chloroform comes out to be non-zero.

The electronegativity difference also exists in the $C-I$ bond, but as chlorine is more electronegative than iodine, so, chloroform ($CHC{{l}_{3}}$) has more dipole moment than iodoform ($CH{{I}_{3}}$).

Hence, the molecule having the largest dipole moment among the given molecules is $CHC{{l}_{3}}$. It possesses a dipole moment of 1.03 D.
Correct Option: (C) $CHC{{l}_{3}}$.

Note: The dipole moment of methane ($C{{H}_{4}}$) and carbon tetrachloride ($CC{{l}_{4}}$) is zero. This is because of their tetrahedron structure. These are symmetrical in nature. In methane, the bond polarity is from hydrogen to carbon, each of which cancels out the other, making the molecule non-polar. Similarly, in carbon tetrachloride, bond polarity is from carbon to chlorine, each of which cancels out the other, making the molecule non-polar.