Abstract
<p> Fe(III) hydrolysis and fluoride complexation behavior was examined in 0.68 molal sodium perchlorate at 25°C. Our assessment of the complexation of Fe(III) by fluoride ions produced the following results: log <sub> F </sub> β <sub> 1 </sub> = 5.15 <sub> 5 </sub> , log <sub> F </sub> β <sub> 2 </sub> = 9.10 <sub> 7 </sub> , log <sub> F </sub> β <sub> 3 </sub> = 11.96, log <sub> F </sub> β <sub> 4 </sub> = 13.7 <sub> 5 </sub> , where log <sub> F </sub> β <sub> n </sub> = 5.15 <sub> 5 </sub> =[FeF <sup> (3-n)+ </sup> <sub> n </sub> ][Fe <sup> 3+ </sup> ] <sup> −1 </sup> [F <sup> − </sup> ] <sup> −n </sup> . The stepwise fluoride complexation constants, <em> F </em> K <sub> <em> n </em> +1 </sub> , obtained in our work (where log <sub> F </sub> <em> K </em> <sub> n+1 </sub> =log <sub> F </sub> β <sub> n </sub> ) indicate that K <sub> <em> n </em> +1 </sub> /K <sub> <em> n </em> </sub> =0.072±0.01. Formation constants for equilibria, Fe <sup> 3+ </sup> +nH <sub> 2 </sub> O⇌Fe(OH) <sup> (3− <em> n </em> )+ </sup> <sub> <em> n </em> </sub> + <em> n </em> H <sup> + </sup> , expressed in the form β <sup> * </sup> <sub> n </sub> <em> [Fe(OH) </em> <sup> (3-n)+ </sup> <sub> n </sub> ] <em> [ </em> H <sup> + </sup> ] <sup> n </sup> <em> ,[Fe </em> <sup> 3+ </sup> ] <sup> -1 </sup> , were estimated as β <sup> * </sup> <sub> 1 </sub> = −2.754, and β <sup> * </sup> <sub> 2 </sub> ≤ −7. Our study indicates that the results of previous hydrolysis investigations include very large overestimates of Fe(OH) <sup> + </sup> <sub> 2 </sub> formation constants.</p>
Original language | American English |
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Journal | Journal of Solution Chemistry |
Volume | 25 |
DOIs | |
State | Published - Jan 1 1996 |
Keywords
- Iron(III)
- ferric
- hydrolysis
- fluoride
- complexation
Disciplines
- Life Sciences