CHCl3, also known as chloroform, is a polar molecule due to its molecular geometry and the difference in electronegativity between the atoms involved.
In CHCl3, the central carbon atom is bonded to three chlorine atoms and one hydrogen atom. Chlorine is more electronegative than carbon, which means it attracts the shared electrons in the C-Cl bonds more strongly. This creates a dipole moment in each C-Cl bond, with the chlorine end being slightly negative and the carbon end being slightly positive.
Although the molecule has a tetrahedral shape, the three C-Cl dipoles do not cancel each other out because they are not symmetrically arranged. The hydrogen atom, being less electronegative, does not significantly counteract the dipoles created by the chlorine atoms. As a result, the molecule has a net dipole moment, making it polar.
In summary, CHCl3 is polar because of the unequal distribution of electron density caused by the difference in electronegativity between carbon and chlorine, and the asymmetrical arrangement of the dipoles.