The compound methanol is a polar molecule. The polarity index of methanol is 5.1, exactly half the index of water. The chemical formula of methanol is CH3OH, and, when diagrammed, the hydroxide end of the molecule forms a significant electrostatic potential.
The polarity of molecules is determined by this electrostatic potential. The strength of the positively and negatively charged ends of the molecule are weighed, and molecules that feature one significant end of each charge form an electrical dipole, making them polar. Other polar substances include dimethyl sulfoxide, which has a polarity index of 7.2, and acetone, which shares the polarity index of methanol.