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

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 [MoO3(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-Ostwald methods. The thermodynamic values, Delta H degrees, Delta G degrees, and Delta S degrees, 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.