Skip to main content

Chemical composition and Gibbs standard free energy of formation of Fe(II)-Fe(III) hydroxysulphate green rust and Fe(II) hydroxide

Buy Article:

$12.42 plus tax (Refund Policy)

The redox potential and pH of aerated suspensions of iron (II) hydroxide in sulphate - containing aqueous solutions are measured during the oxidation process. Plateaux corresponding to the equilibrium conditions between Fe(OH)2(s) and Fe(II)-Fe(III) hydroxysulphate GR2(SO42-)(s) on the one hand, and between GR2(SO42-)(s) and FeOOH(s) on the other hand, are displayed. Potentiometry, voltammetry, pH-metry and Mössbauer spectroscopy are applied to follow all reactions. The thermodynamic meaning of the measured potential of the first plateau which corresponds to the GR2(SO42-)(s) /Fe(OH)2(s) equilibrium is demonstrated. The chemical composition of GR2(SO42-)(s) is found to be Fe4IIFe2III(OH)12SO4.nH2O all along the oxidation process, implying that this compound must be considered as a pure phase with a well-defined composition. The Gibbs standard free energy of formation or chemical potential °[GR2(SO4-)(s)] in "anhydrous form" (n = 0) is determined at -3790 ± 10 kJ mol-1. A consistent value of °[Fe(OH)2(s)] at -490 ± 1 kJ mol-1 is obtained.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Document Type: Research Article

Publication date: 1999-09-01

More about this publication?
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
UA-1313315-23
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more