A solvent is a substance that dissolves another substance, forming a solution. The polarity of a solvent can be determined by its dielectric constant, with values less than 15 generally being non-polar and greater than 15 being polar. Polar solvents can be further divided into protic and aprotic types. Protic solvents can form hydrogen bonds, while aprotic solvents cannot form hydrogen bonds but are still polar. Semi-polar compounds can act as intermediate solvents to bring about miscibility between polar and non-polar solvents. Miscibility refers to the mutual solubility of components in liquid-liquid systems, with polar/semi-polar and non-polar solvents being completely miscible.

1. Mr.Halavath Ramesh
16-MCH-001
Department of Chemistry
Loyola College-chennai.

2.  Solvent : A solvent is a substance that dissolves a solute resulting in a
solution. A solvent is usually a liquid but can also be a solid, a gas or a
super critical fluid. When one substances is dissolved into another a
solution is formed.
 Generally the dielectric constant of the solvent provides a rough measure
of a solvents polarity.
 The strong polarity of water is indicated its high dielectric constant of
88(at 0oc)
 Solvents with a dielectric constant of less than 15 are generally
considered to be non-polar.
 Solvents with dielectric constant of greater than 15 are called polar
solvents.
 Polar solvents can be divided into two types
 1. Protic solvent
 2. Aprotic solvent

4. Polar Solvent: Polar solvents contain bonds between atoms with very different electro negativities ,
such as oxygen and hydrogen and have large dipole moment.
Non-Polar Solvent: Non- polar solvents contain bonds between atoms with similar electro negativities
such as carbon and hydrogen.
These polar solvents are capable of forming hydrogen bonds with water to dissolve in water whereas non-
polar solvents are not capable of strong hydrogen bonds.
Polar Protic solvent: Polar Protic solvents are capable of forming hydrogen bonding because they
Contain at least one hydrogen atom connected directly to an electronegative atom( such as O-H or
N-H bonds).They solvate Cation and anions effectively. Polar Protic solvents are water, ethanol,
methanol,ammonia,acetic acid and other.

5. Polar Aprotic solvent: Polar Aprotic solvents are contain no hydrogen atoms
connected directly to an electronegative atom and they are not capable of hydrogen
bonding .These are acetone, dimethyl sulfoxide(DMSO),DMF(N,N-Dimethyl
formide ,Acetonitrile,HMF(Hydroxy methyl furfural ,crown ether and other)

8.  In fact semi polar compounds can act as
intermediate solvents to bring about
miscibility of polar and non polar solvent.
 partly polar —used especially of chemical
bonds and structures regarded as possessing
polarity associated with nonpolar covalence
(as in an amine oxide R3N+−O−)


9.  The term miscibility refers to the mutual solubility of the
components in liquid –liquid systems.
 Polar and semi polar solvents, such as water and alcohol, Glycerin
and alcohol, alcohol and acetone are said tobe completely miscible
because they mix in all proportions.
 Non-polar solvents such as benzene and carbon tetra chloride are
also completely miscible.