Studies on the Use of Coulometric and Amperometric Analysis
<p>A coulometric titration is described in which unipositive thallium is oxidized to the tripositive state by electrolytically generated bromine or chlorine. The end-point is determined amperometrically by measuring the current between two platinum electrodes with an impressed potential d...
| Summary: | <p>A coulometric titration is described in which unipositive
thallium is oxidized to the tripositive state by electrolytically
generated bromine or chlorine. The end-point is determined
amperometrically by measuring the current between
two platinum electrodes with an impressed potential difference
of 200 millivolts. Confirmatory analyses have shown an accuracy of 0.2% for 93
to 200 microgram samples, and of 0.1%
for samples of from 200 to 1900 micrograms.</p>
<p>The application of dual intermediates to secondary coulometric titrations
with an amperometric end point has been studied.
Cupric copper and bromide have been used for the alternate electrolytic
generation of bromine and cuprous copper for the purpose of titrating
a substance exhibiting a slow rate of reaction with bromine.
A procedure is described by which aniline has been titrated in
quantities of from 13 to 280 micrograms with an average error without regard
to sign of less than 0.4 micrograms.</p>
<p>A study has been made of the bromine-bromide diffusion current,
the effects of the concentrations of bromine, bromide
and hydrogen ion; the minimum bromide ion concentration necessary
to maintain generation of bromine with 100% current efficiency was determined.</p>
<p>Studies have been made of the diffusion-controlled currents observed when potential
differences, less than the decomposition potential, are impressed upon two
platinized-platinum electrodes in solutions of hydrochloric acid which are 0.1 VF
in potassium chloride and saturated with hydrogen gas. The effects of the
electrode size and material, the applied potential, and the presence of
oxygen and nitrogen gas are described.</p> |
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