In another experiment, in
which 50 c.c. of the ferrous sulphate solution were titrated with
"permanganate," 48 c.c. of the latter were required. The titrated
solution was next reduced with sulphuretted hydrogen, brought to the
same bulk as before, and again titrated; 47.9 c.c. of the permanganate
of potassium solution were required.
(3) _With Sodium Sulphite._--Twenty c.c. of the ferric chloride
solution, reduced with sodium sulphite, required 19.9 c.c. of
"permanganate." In one experiment 50 c.c. of the ferrous sulphate
solution were titrated with "permanganate"; 49.3 c.c. of the
last-mentioned solution were required. The titrated solution was reduced
with sodium sulphite, and again titrated; it required 49.2 c.c. of the
permanganate of potassium solution.
(4) _With Zinc._--Twenty c.c. of the ferric chloride solution, reduced
with zinc and titrated, required 20.8 c.c. of "permanganate." Fifty c.c.
of a solution of ferrous sulphate which required 49.7 c.c. of
"permanganate," required for re-titration, after reduction with zinc,
49.7 c.c.
The student should next practise the titration with bichromate, which is
more especially valuable in the estimation of hydrochloric acid
solutions. The following experiments are on the same plan as those
already given. In each experiment (except when otherwise stated) there
were present 20 c.
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