This document discusses conductometric titration, which is a quantitative analysis method used to determine the concentration of an analyte in a mixture by measuring electrical conductivity changes during a titration. It describes different types of titrations including strong acid with strong base, weak acid with strong base, strong acid with weak base, and weak acid with weak base. Break points, curves, and plateau regions are discussed for each type of titration. Displacement and precipitation titrations are also summarized. Finally, the general procedure for a conductometric titration of an acid with a base is outlined.

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Conductometric Titration
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It is the lab method of quantitative
analysis used to identify the
concentration of a given analyte in
mixture.
Note: This titration follows the fact that
the electrical conductivity of an
electrolytic solution is dependent on the
number of free ions in the solution and
the charge corresponding to each of
these ions.

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1.Strong Acid with a Strong Base
e.g. HCl and NaOH
• Before NaOH is added, the conductance is
high due to the presence of highly mobile
hydrogen ions.
• When the base is added, the conductance
falls due to the replacement of hydrogen ions
by the added cation as H+ ions react with
OH− ions to form undissociated water.
• This decrease in the conductance continues
till the equivalence point. At the equivalence
point, the solution contains only NaCl.
• After the equivalence point, the conductance
increases due to the large conductivity of
OH- ions
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• Initially the conductance is low due to the feeble
ionization of acetic acid.
• On the addition of base, there is decrease in
conductance not only due to the replacement of H+
by Na+ but also suppresses the dissociation of
acetic acid due to common ion acetate. But very
soon, the conductance increases on adding NaOH
as NaOH neutralizes the un-dissociated CH3COOH
to CH3COONa which is the strong electrolyte.
• This increase in conductance continues raise up to
the equivalence point. The graph near the
equivalence point is curved due the hydrolysis of
salt
• CH3COONa. Beyond the equivalence point,
conductance increases more rapidly with the
addition of NaOH due to the highly conducting OH−
ions
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2. Weak Acid with a Strong Base
e.g. Acetic Acid and NaOH

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3. Strong Acid and Weak Base
e.g. H2SO4 and Dil. Ammonia
• Initially the conductance is high and
then it decreases due to the
replacement of H+.
• But after the endpoint has been
reached the graph becomes almost
horizontal
• Since the excess aqueous
ammonia is not appreciably ionised
in the presence of ammonium
sulphate.

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• The nature of curve before the
equivalence point is similar to the
curve obtained by titrating weak
acid against strong base.
• After the equivalence point,
conductance virtually remains same
as the weak base which is being
added is feebly ionized and,
therefore, is not much conducting.
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4. Weak Acid and Weak Base
e.g. Acetic Acid and Ammonia

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5.Mixture of a Strong Acid and a Weak Acid vs. a
Strong Base or a Weak
Base • In this curve there are two break points. The
first break point corresponds to the
neutralization of strong acid.
• When the strong acid has been completely
neutralized only then the weak acid starts
neutralizing.
• The second break point corresponds to the
neutralization of weak acid and after that the
conductance increases due to the excess of
OH− ions in case of a strong base as the
titrant.
• However, when the titrant is a weak base, it
remains almost constant after the end point.
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• When a salt of a weak acid is titrated with a strong
acid, the anion of the weak acid is replaced by that
of the strong acid and weak acid itself is liberated in
the undissociated form.
• Similarly, in the addition of a strong base to the salt
of a weak base, the cation of the weak base is
replaced by that of the stronger one and the weak
base itself is generated in the undissociated form.
• The initial increase in conductivity is due to the fact
that the conductivity of the chloride ion is slightly
greater than that of acetate ion.
• Until the replacement is nearly complete, the solution
contains enough sodium acetate to suppress the
ionization of the liberated acetic acid, so resulting a
negligible increase in the conductivity of the solution.
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6. Displacement (or Replacement) Titrations

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7. Precipitation Titration and Complex
Formation Titration:
• A reaction may be made the basis
of a conductometric precipitation
titration provided the reaction
product is sparingly soluble or is a
stable complex.
• The solubility of the precipitate (or
the dissociation of the complex)
should be less than 5%.
• The addition of ethanol is
sometimes recommended to reduce
the solubility in the precipitations.

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• 10 ml of the acid must be diluted with
approximately 100 ml of distilled water (so that
the changes in the conductance brought on by
the addition of the base become small).A
burette must now be filled with the base and the
initial volume must be noted.
• In this step, a conductivity cell must be inserted
into the diluted acid solution in a way that both
the electrodes are completely immersed.
• Now, the conductivity cell can be connected to a
digital conductometer in order to obtain an initial
reading.
• The base must now be added dropwise into the
acid solution. The volume of base added must
be noted along with the corresponding change
in the conductance.
• A sharp increase in the conductance of the
solution implies that the endpoint has been
reached. However, a few more readings must
be taken after the endpoint of the titration.
• These observed values must now be plotted
graphically. The equivalence point can be
obtained from the point of intersection between
the two lines.
• The strength of the acid can now be calculated
via the formula S2 = (V1S1)/10; where S2 is the
strength of the acid, V1 is the volume of base
added (as per the equivalence point on the
conductometric titration graph), and S1 is the
strength of the base (already known). Here, the
volume of the acid (V2) is equal to 10 ml.
For the conductometric titration of an acid with
a base, the general process is as follows:
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