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.
