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| Arrhenius theory of ionization consists of the following postulates. | ||
 The
substance called electrolytes are believed to contain electrically charged
particles called ions. These charges are positive for
H+ ion or ions derived from metals and negative for the ions
derived from non-metals. Number of electrical charges
carried by an ion is equal to the valency of corresponding
atom. |
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Molecules
of electrolytes (acids, bases and salts) dissociate into oppositely charged
ions on dissolution in water, e.g. |
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NaCl
 Na+
+Cl-HCl
H+ +Cl-NaOH
Na+ + OH- |
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| The
number of positive and negative charges on the ions must be equal so that
the solution as a whole remains neutral. |
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| In
solution, the ions are in a state of disorderly or random motion. Upon colliding
they may combine to give unionized molecules. Thus ionization
is a reversible process in which the solution contains ions of electrolyte
together with unionized molecules. |
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H2SO4(aq)
2H+(aq) + SO4-2(aq) |
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The
extent of ionization or the degree of ionization depends upon the nature
of electrolyte.Strong electrolytes such as HCl etc. ionize
completely in water. Weak electrolytes such as acetic acid (CH3COOH)
ionize only slightly |
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| Ionization
is not affected by electric current. |
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| When
electric current is passed through an electrolytic solution, charges move
towards their respective electrodes, i.e. cations towards
anode and anions towards cathode.When these ions reached
their respective electrodes, they change into neutral species by the gain
or loss of electron. |
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| The
dissociation of electrolyte depend upon Nature of electrolyte Degree of dilution Temperature |
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The
electrical conductivity depends upon : The number of ions present in the solution Speed of ions |
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