3. Potentiometric titrations
End point of titrations can be determined by measuring
changes in potential of a solution caused by addition of
titrant.
Potentiometric titrations have many advantages-
◦ Colored solutions, dil. Solutions or turbid suspensions can be
titrated.
◦ Titration can be automated.
◦ Mixture of components can be titrated
◦ More accuracy, etc.
4. Method of detecting end method;
There are different methods adopted to locate the end
point.
The critical problem in location of end point is to know
the point at which the quantities of reacting species are
present in equivalent amounts at the equivalence point.
It is generally found graphically.
There are three methods used for this purpose.
5.
6. 1.
In the first method values
of e.m.f. (E) or pH
recorded on graph paper as
ordinate and the volume of
titrant (V) added.
In this graph when we get a
maximum slop of curve,
that point will be termed as
end point of this method.
7. 2.
In the second method,
difference of e.m.f. or pH
for the volume of titrant
added is plotted as
ordinate versus the
volume of titrant added.
In this method, also get an
end point at where
maximum change in graph
occurs.
