D7318_10
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Measure the exact concentration
of the lead nitrate titrant
by titration of the
sulfate standard,
8.2 of the written standard.
Transfer 1.00 milliliters of
the 0.01 molar aqueous sulfate
standard solution, 8.2
of the written standard,
into a 150-milliliter beaker.
Record this volume as V. Add
approximately 100 milliliters
of denatured ethanol, 7.4
of the written standard,
and 1 milliliter of 0.1
molar perchloric acid, 8.6
of the written standard.
Prepare the autotitrator
for operation.
Immerse the electrodes in
the titration solution.
Initiate stirring and titrate
to the potentiometric endpoint
with lead titrant.
Titration should require
approximately 4.0 milliliters
of lead solution to
reach the endpoint.
Record this volume as T. Titrate
a blank denatured ethanol
sample in the same
manner without addition
of sulfate standard.
Record this volume as T sub b.
Calculate the concentration
of the lead nitrate titrant
as shown in equation 4
of the written standard.
The standardization should
be repeated until precision
comparable to that shown
in section 15 and table
2 of the written standard has
been achieved, where M sub
Pb equals molarity of lead in
the titrant, moles per liter;
V equals volume of
sulfate standard solution
added, milliliters, 10.1.1
of the written standard;
S equals molarity of
the sulfate solution
from 8.2 of the written
standard, moles per liter;
T equals volume of lead
titrant used to titrate
the sulfate solution,
milliliters;
and T sub b equals the
volume of lead titrant used
for the blank, milliliters,
10.2 of the written standard.