Reaction of Hydrogen Peroxide with Titanium (IV) at Different pH Values

Abstract

Abstract Reaction of hydrogen peroxide with titanium(IV) has been investigated over the range of pH 0 to 13. Below pH 2 this reaction gives orange-colored ion-species, [Ti(OH)2(H2O)(H2O2)]2+ or (TiO2·-aq)2+. In the range of pH 3 to 6 formation of a yellow species is observed and its chemical formula is presumed to be [Ti(OH)3(H2O2)]+. Existence of a species different from the above is indicated by the pale yellow color observed in the region of pH 7 to 9. This species is very unstable unless a large excess of hydrogen peroxide is present, and its chemical formula is presumed to be [Ti(OH)3(OOH)]0. At higher pH values (10<pH), the reaction mixture is colorless, and presumably contains [Ti(OH)2(O2)2]2−. All the tentative formulae of these species are based on the composition of isolated salts, the absorption spectra of the solutions etc. A solution containing [Ti(OH)2(H2O)(H2O2)]2+ remains unchanged but a solution containing [Ti(OH)3(H2O2)]+ gives a yellow precipitate TiO(OH)(OOH), and one containing [Ti(OH)3(OOH)]0 or [Ti(OH)2(O2)2]2− gives a pale yellow compound (Remark: Graphics omitted.) at room temperature or more quickly when heated on a water-bath. The precipitation reaction of (Remark: Graphics omitted.) is taken advantage of in a new volumetric analysis suited for determination of titanium in quantities of the order of 10 mg.