Polar solvents are solvents that contain partial positive and partial negative charges, or in other words, they must have a dipole moment. They are liquids with molecules that have a slight electrical charge due to their shape. Examples of polar solvents include water, methanol, and ethanol/Fundamentals/Intermolecular_Forces/Polar_Protic_and_Aprotic_Solvents). Polar solvents are best for dissolving polar reactants such as ions, while nonpolar solvents are best for dissolving nonpolar reactants such as hydrocarbons. Polar solvents are also used to dissolve polar materials such as salt and sugar, which dissolve easily in water, the Earths most common polar solvent. Polar solvents will not normally dissolve nonpolar materials, and vice versa. The term "like prefers like" is often used to note the preference of polar materials for polar solvents, and similarly for nonpolar materials.