Short communication, Note

Coulombic Retardation Effect of »Neutral« Electrolytes on Formation of Barium Sulfate Crystallites (Reversal of Schulze-Hardy Rule)

B. Težak ; Laboratory of Physical Chemistry, Faculty of Science, University of Zagreb
B. Novosel ; Laboratory of Physical Chemistry, Faculty of Science, University of Zagreb

Abstract

The formation of precipitates by mixing the diluted solutions
of barium nitrate and sodium sulfate (w ith sulfate in excess) and
in presence of various concentrations of potassium, magn esi um,
and lanthanum nitrate, was followed tyndallometricall y. It was
found that there are critical concentrations of counter ions of the
s ame order as with Schulze-Hardy rule but of opposite effect: at
higher concentrations there was a distinct retardation in the
formation of particles. The effect may b e. explained as the result
of coulombic interactions in the formation of ion pairs or complexes
between sulfate and cou'nter ions causing either a slower embrionation,
or a hindrance of direct growth, and/ or a retardation of
the aggregation of growing nuclei into l arger crystallites.

Keywords

Hrčak ID:

208066

URI

https://hrcak.srce.hr/208066

Publication date:

15.5.1968.

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