What Is a Non-Aqueous Solvent?
A solvent is a substance that dissolves a solute in the formation of a solution, and any solvent other than water is considered a non-aqueous solvent. Some common examples include ether, alcohol, benzene, disulphide, carbon tetrachloride and acetone. While water is a useful solvent for investigating acid-base properties, the differences between water and other solvents mean that non-aqueous solvents often provide more realistic experimental outcomes.
Water has a dielectric constant that is higher than many other solvents, which means that it has a greater ability to decrease the force existing between two electric charges. Water also has the ability to act as either a base or an acid, which also sets it apart from other solvents.
As far as non-aqueous solvents go, they belong in one of four categories: amphoteric, both basic and acidic; acidic; basic or aprotic, meaning that the solvent acts neither as an acid or base. The most commonly used amphoteric solvents include ethanol and methanol, which have similar acid-base properties to water but produce fewer ions because of their lower dielectric constants.
Acidic solvents protonate many different compounds that have nitrogen or oxygen, and the strongest one is sulfuric acid. This means that all compounds with those two elements act like bases when in sulfuric acid. The only commonly used basic solvent is liquid ammonia, which levels out the acidity of such solvents as nitric, hydrochloric and acetic acids.