Project Watershed Central New York

A solvent is a liquid that dissolves a solute. The solvent is the component of a solution that is present in greater amount. See solution.

Perhaps the most common solvent in everyday life is water. Many other solvents are organic compounds, such as benzene, tetrachloroethylene or turpentine.

Solvents can be broadly classified into polar and non-polar solvents. Common polar solvents include water and ethanol. Generally polar or ionic compounds will only dissolve in polar solvents. A test for the polarity of a liquid solvent is to rub a plastic rod, to induce static electricity. Then hold this charged rod close to a running stream of the solvent. If the path of the solvent deviates when the rod is held close to it, it is a polar solvent.

In chemistry, a common rule for determining if a solvent will dissolve a given solute is "like dissolves like." Solvents composed of polar molecules, such as water, dissolve other polar molecules, such as table salt, while nonpolar solvents, such as gasoline, dissolve nonpolar substances such as wax. The degree that a solvent dissolves a given solute is known as its solubility. Ethyl alcohol is highly soluble in water, for example. Vinegar is very insoluble in oil, and the two substances will quickly separate into two layers even after being shaken well. Liquids that separate in such a way are qualified as immiscible.

A solvent will create various weak chemical links with the solute in order to solubilize it. The most common of these weak interactions are hydrogen bonding (interaction between a hydrogen atom on a polar solvent to a nitrogen or oxygen atom of the solute) and van der Waals interaction. Hydrogen bonding is one of the principal mechanism by which water solubilize so many polar compounds.