of precipitate formed but also the complete coagulation of the
jelly like product obtained. The results, taking into account the
possible chemical composition of the precipitate, are shown in
Table 2.
Considering the two possible identities for the precipitate, the
results were quantitative for both standards being the best ones a
result of using a molar relationship cation:base of 1:2 and not the
expected 1:3 for the hydroxide. Based on these results the exact pH
of the mixture seemed to be more important than the molar relation
between the reagents. Commercial flocculating products were
used and the results are shown in Table 3. In this case the identity
of the precipitate obtained is unknown due to the characteristics
of the coagulant and flocculant used; if the same compositions of
the product are considered, this process was quantitative as well.
Preliminary experiments showed that the initial concentration of
the cation is very important in order to be able to isolate the flocculated
product because of its jelly consistency and exact pH of
redissolution.