Abstract: | The formation of 1 : 2 titanium(III) complex with chromotropic acid (4, 5-dihydroxy-2, 7-naphthalene-disulfonic acid) was observed by spectrophotometric measurements at various ionic strengths. An expression, Ti(III)]/D=1/Δ? + αH2+/KΔ?H2R2?]2, was derived for the determination of the formation constant, K=7.2×102 liter2 mol?2 for the Ti(III).(HR)2 ion in the pH range of 1.3–1.8 at constant ionic strength, I=0.2 M, at 25°C. The thermodynamic data for the reaction, Ti(III)+2H3R2?=Ti(III) (HR)2+2H+, were calculated to be ΔG° = ?16 kJ mol?1 ΔH° = 18 kJ mol?1, ΔS° = 110 JK?1 mol?1, at 25°C. |