Iron hydrolysis and solubility revisited: observations and comments on iron hydrolysis characterizations

摘要: Abstract This work describes and evaluates previous hydrolysis characterizations relevant to the behavior of iron in natural solutions, with special emphasis given physical chemistry seawater. New potentiometric data are used this extend FeOH 2+ constant 6 M ionic strength. These results obtained NaClO 4 excellent agreement spectrophotometric over range conditions those works. The enthalpy for first Fe 3+ step (Δ H 1 *) is 10.2 kcal mol −1 molal scale appropriate ( β *=[FeOH ][H + ][Fe ] ) log *=−2.71±0.03 at 25°C strength Recalculations data, as well new experimental analyses indicate that Fe(OH) 2 constants *=[Fe(OH) [Fe strengths between 0.7 3.0 on order *≤−7. is, like *, expected be strongly temperature-dependent *≅16.9 ). Previous estimates 3 * derived from solubility operationally defined model-dependent. At seawater estimated *≤−13.6. Enthalpy *≅23.9 upper bound decreases decreasing temperature. Our current understanding pH dependence III closely tied assumptions about form 3(s) products aqueous solution. Evidence presented which indicates product, K so *=[Fe − n , should written