What is a polar solvent and what is a non-polar solvent?

A polar solvent is one in which the molecules possess a positive and a negative end (dipole), whereas a non-polar solvent is one in which the molecules do not possess a net dipole.

Polar solvent

• Definition: A solvent whose molecules have an uneven electrical charge distribution and thus a permanent dipole moment.
• Molecular features: presence of polar bonds (e.g. O-H, C=O), asymmetrical shape so dipoles do not cancel.
• Solvent behaviour: high dielectric constant, good ability to dissolve salts or ionic compounds, hydrogen bonding possible.
• Examples: Water (H₂O), methanol, acetone.

Non-polar solvent:

• Definition: A solvent in which the molecules have little or no permanent dipole moment (i.e., charge distribution is nearly symmetric).
• Molecular features: carbon–carbon or carbon–hydrogen bonds with low electronegativity difference, symmetrical shape so any small dipoles cancel out.
• Solvent behaviour: lower dielectric constant, good for dissolving non-polar substances (oils, waxes), weaker intermolecular interactions.
• Examples: Hexane, benzene, carbon tetrachloride (CCl₄).