Types of Electrolytes:
The compounds which give ions either in molten state or in solution are called electrolytes. In the solid state they are bad conductors, but become good conductors either in the molten state in solution.
There are two types of electrolytes:
(1) Strong electrolytes:
These electrolytes are almost completely ionized when dissolved in a polar medium like water. In solution they are excellent conductors, e.g., HNO3, HCl, KOH, NaOH, etc. Their degree of ionization is high and approaches unity.
(2) Weak electrolytes:
These are not completely ionized when dissolved in a polar solvent and they behave as poor conductors of electricity, e.g., CH3COOH, H3PO4, H3BO3, NH4OH, etc., Equlibrium between ions and unionized molecules is established in solution, e.g.,
CH3COOH ↔ CH3COO- + H+
The above equilibrium is termed as ionic equilibrium. Degree of ionization of weak electrolytes is much less than unity.
Degree of ionization 'α' may be defined as a fraction of tital number of molecules of an electrolyte which dissociate into ions.
α = %ionization/100
= (Number of molecules dissociated as ions)/(Total number of molecules of electrolyte dissolved)
The following classification of electrolytes is based on their behavior in a particular solvent, i.e., water.
Conduction (solutions of Non-conducting electrolytes , i.e., acids,
electrolytes i.e. acids, bases (Solution of non-electrolytes such as
and salts) urea, glucose, sugar, glycerine, etc.)
Strongly conducting (solns. of Weakly conducting
Strong electrolytes which ionize (solutions of weak ele-
Almost completely in water such ctrolytes which slightly
as HCl, H2SO4, HNO3, NH4Cl, ionize in water such as
NaCl, NaOH, KOH, etc.) CH3COOH, NH4OH, H3PO4, HCN, etc.)
However, an electrolyte may behave as a strong one in aqueous solution, but it may behave as a weak one in another solvent. For example, sodium chloride behaves as a strong electrolyte and acetic acid as a weak electrolyte when dissolved in water but their conducting abilities are comparable in liquid ammonia solvent.