Question

Why is $HCl$ is polar while $C{l_2}$ molecule is nonpolar ?

Answer 1

Polar molecules are those molecules which have polarity of charge on them while non-polar compounds are those which do not have polarity of charge on them. The polarity comes due to the electronegativity difference between two bonded atoms. We will observe the electronegativity difference and then depict why $HCl$ is polar while $C{l_2}$ molecule is nonpolar.

Complete Step By Step Answer:
Polar compounds are those compounds which have some polarity of charge on each atom of the compound. These charges' polarity comes due to the difference of the electronegativity of the atoms bonded together. The bond between them is also known as polar bond. Like $HCl$ is a polar compound because there is an electronegativity difference between hydrogen and chlorine. Where non-polar compounds are those which do not have polarity of charges on its constituent atoms. They may have partially charged. Like in case of chlorine $C{l_2}$ , there is no electronegativity difference between both chlorine atoms. Thus we can say that it is non-polar in nature. The $HCl$ will be dissociated as:
$HCl{\text{ }} \to {\text{ }}{H^ + } + C{l^ - }$
But chlorine will not be dissociated as above. It may dissociate as free radical in the presence of sunlight.
$C{l_2}{\text{ }}\xrightarrow{{hv}}{\text{ }}C{l^ \circ } + {\text{ }}C{l^ \circ }$
Therefore hydrochloric acid is polar while chlorine gas is non-polar in nature.

Note:
It must be noted that all ionic compounds are polar in nature but all covalent compounds are not polar in nature. The covalent compounds which have electronegativity differences between the atoms are polar in nature while others are non-polar in nature. Polar compounds dissolve in water while non-polar compounds do not dissolve in water.