Solvent

A solvent is a substance, usually a liquid, that dissolves another substance—called the solute—at the molecular level, forming a homogeneous mixture called a solution. In a solution, the solvent is typically the component present in the largest amount.

The dissolving process does not require a chemical change to occur. Solvent molecules interact with the molecules or ions of the dissolved substance and then break apart the bonds holding them together. The power of a solvent depends on the type of molecular bonding it has, particularly whether it is polar or nonpolar.

Classification of solvents

Solvents are generally divided into two broad categories. Polar solvents—such as water and alcohol—dissolve salts and ionic substances well. Nonpolar solvents—such as hydrocarbons and oils—dissolve fats, waxes, and similar substances. The general rule that follows is "like dissolves like."

Water

Water is known as the universal solvent because of the large number of substances it can dissolve. The polar nature of the water molecule and its hydrogen bonding enable it to dissolve many salts. All biological life depends on reactions that occur in aqueous solutions.

Industrial use

Solvents are used in paints and varnishes, cleaning and soap production, pharmaceuticals and chemical manufacturing, and the extraction of plant-based substances. Industrial plants also use solvents to remove oily contaminants from materials.

Health and safety

Most natural solvents evaporate quickly, and some are highly flammable. Inhalation of vapors or prolonged skin contact can affect the lungs, liver, and kidneys. For this reason, workplaces are required to have proper ventilation, protective clothing, and regulated exposure limits.