SOLVENT

Definition

solvent: A liquid that dissolves anothersubstance or substances toform a solution. Polar solvents arecompounds such as water and liquidammonia, which have dipole momentsand consequently high dielectricconstants. These solvents arecapable of dissolving ionic compoundsor covalent compounds thationize. Nonpolar solventsare compounds such asethoxyethane and benzene, which donot have permanent dipole moments.These do not dissolve ioniccompounds but will dissolve nonpolarcovalent compounds. Solvents canbe further categorized according totheir proton-donating and acceptingproperties. Amphiprotic solvents selfionizeand can therefore act both asproton donators and acceptors. A typicalexample is water:
2H₂O?H₃>O⁺ + OH^-
Aprotic solvents neither accept nor donate protons; tetrachloromethane(carbon tetrachloride) is an example.

Definition

A liquid capable of dissolving other materials (solids, liquids, or gases) to form a solution. The solvent is generally the major component of the solution. Solvents can be divided into classes, the most important being:
Polar. A solvent in which the molecules possess a moderate to high dipole moment and in which polar and ionic compounds are easily soluble. Polar solvents are usually poor solvents for non-polar compounds. For example, water is a good solvent for many ionic species, such as sodium chloride or potassium nitrate, and polar molecules, such as the sugars, but does not dissolve paraffin wax.
Non-polar. A solvent in which the molecules do not possess a permanent dipole moment and consequently will solvate non-polar species in preference to polar species. For example, benzene and tetrachloromethane are good solvents for iodine and paraffin wax, but do not dissolve sodium chloride.
Amphiprotic. A solvent which undergoes self-ionization and can act both as a proton donator and as an acceptor. Water is a good example and ionizes according to:
2H₂O = H3O⁺ + OH^–
Aprotic. A solvent which can neither accept nor yield protons. An aprotic solvent is therefore the opposite to an amphiprotic solvent.