THERMODYNAMIC PROPERTIES OF THE AQUEOUS IONS (2+ AND 3+) OF IRON AND THE KEY COMPOUNDS OF IRON

Recommended thermochemical property values, Delta(f)H degrees, Delta(f )G degrees, and S degrees for the aqueous ions of iron, Fe2+ and Fe3are given at 298.15 K in SI units. They are consistent with the CODATA Key Values for Thermodynamics. The values are: Delta(f)H degrees = -9 0.0 +/- 0.5 kJ . mol(-1), Delta(f)G degrees = -90.53 +/- 1.0 kJ . mol( -1), S degrees = -101.6 +/- 3.7 J . mol(-1) . K-1 for Fe2+ (ao) and De lta(f)H degrees = -49.0 +/- 1.5 kJ . mol(-1), Delta(f)G degrees = -16. 28 +/- 1.1 kJ . mol(-1), S degrees = -278.4 +/- 7.7 J . mol(-1) . K-1 for Fe3+(ao). The evaluation involves the analysis of the enthalpy cha nges, Gibbs energy changes, and the entropy measurements for all key s ubstances in the key network. A consistent set of thermochemical prope rty values is given for FeOOH(cr, Goethite), FeCl2(cr), FeCl3(cr), FeB r2(cr), FeBr3(cr), FeI2(cr), and FeSO4 . 7H(2)O(cr), as well as ''reco nstituted'' recommended process values with uncertainties involving th ese substances. All recommended values are also given for a standard s tate of p degrees = 1 arm. A computer based reaction catalog of measur ements accompanies the text analysis. (C) 1995 American Institute of P hysics and American Chemical Society.