Spectrophotometric study of the reaction of molybdenum (Ⅵ) with sodium-pyrogallol-5-sulphonate. The determination of molybdenum

摘要

On the basis of spectrophotometric measurements and applying the Job, Harvey- Manning, mole ratio and the Franck-Ostwald methods it has been found that, in acid media, molybdenum (Ⅵ) and sodium-pyrogallol-5-sulphonate (PS) form a complex [MoO_3(PS)_2]~2. The wide absorption maxima of this complex is at 314-375 nm. The stability constants of this complex were calculated by using the Job and the Franck-Ost- wald methods. The thermodynamic values, △H~o, △G~o, and △S~o, of the complex have also been calculated. A spectrophotometric method for molybdenum determination has been developed. The method is applied for the determination of molybdenum in steel.