A method for sorbing a gas using an ionic liquid to sorb a vapor having an electric multi-pole moment. The ionic liquid comprises an anion and a cation. The electric multi-pole moment may be an electric dipole moment and/or an electric quadru-pole moment. The sorption may be an adsorption or an absorption. The ionic liquid may be a liquid that substantially contains only anions and cations, while not containing other components, such as water. Alternatively, a solution containing the ionic liquid and a solvent or further compound, such as water, may be used.