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Über die Hydrolyse von Eisen(III)‐perchlorat‐Lösungen
Author(s) -
Feitknecht W.,
Michaelis W.
Publication year - 1962
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19620450127
Subject(s) - chemistry , amorphous solid , crystallization , base (topology) , perchlorate , deprotonation , hydroxide , colloid , metastability , ion , induction period , hydrolysis , inorganic chemistry , polymer chemistry , crystallography , catalysis , organic chemistry , mathematical analysis , mathematics
The authors investigate the reaction products formed, when Fe(H 2 O) 3 6 + is deprotonated in perchlorate solutions. When a small amount of base is added, metastable solutions containing the ions Fe(H 2 O) 3+ , Fe(H 2 O) 5 OH 2+ , Fe 2 (H 2 O) 8 (OH) 4+ and Fe(H 2 O) 4 (OH) + are formed, and α‐FeOOH slowly crystallises out. In a narrow intermediate range immediately after adding the base, colloidal amorphous Fe(OH) 3 and crystalline α‐FeOOH are formed. If more base is added a dark brown solution of colloidal amorphous Fe(OH) 3 results, in which the crystallisation of α‐FeOOH, under certain conditions also of γ‐FeOOH, begins after an induction period of several days. Only when a nearly equivalent amount of base is added, Fe(OH) 3 is precipitated. On ageing, this changes partly into α‐Fe 2 O 3 , partly into α‐FeOOH, a rather large amount remaining amorphous. In all the systems, no stable state is reached at room temperature, even after years. If a small amount of Fe 2+ ions is coprecipitated, a complete crystallisation of the amorphous hydroxide to α‐FeOOH takes place. The mechanism of the formation of the crystalline phases is discussed.