Abstract
The reaction between iron(III) and Xylenol Orange (XO or $H_6A$) has been investigated spectrophotometrically. It has been established that iron (III) and XO form two complexes with compositions iron(III) : XO = 2 : 1 and 1 : 1. The 2 : 1 complex is stable in acidic medium containing excess of iron, and 1 : 1 complex is stable in slightly acidic medium containing excess of XO. The absorption maxima are at 590 nm (2 : 1) and 500 nm (1 : 1), the molar absorptivities being $3.18{\pm}0.04{\times}10^4,\;1.32{\pm}0.03{\times}10^4$respectively. The stability constants of two complexes studied by varying pH are $loglog{\beta}_{21}=18.69{\pm}0.03,\;log{\beta}_{212}=42.08{\pm}0.09,\;log{\beta}_{11}=4.17{\pm}0.04,\;and\;log{\beta}_{113}=34.47{\pm}0.07.$
Fe(III)과 Xylenol Orange (XO 또는 $H_6A$)의 반응을 분광광도법으로 연구하였다. Fe(III)과 XO는 조성이 Fe(III) : XO = 2 : 1 및 1 : 1 인 두가지 착물을 형성함을 확인하였다. 2 : 1 착물은 XO보다 Fe(III)를 많이 포함한 산성에서 안정하고, 1 : 1 착물은 XO가 많이 포함된 약산성용액에서 안정하다. 흡수극대는 590nm(2 : 1)와 500nm(1 : 1)이고 몰흡광계수는 각각 $3.18{\pm}0.04{\times}10^4,\;1.32{\pm}0.03{\times}10^4$이다. pH값을 변화시키면서 측정한 두 착물의 안정도상수는 $log{\beta}_{21}=18.69{\pm}0.03,\;log{\beta}_{212}=42.08{\pm}0.09,\;log{\beta}_{11}=4.17{\pm}0.04,\;and\;log{\beta}_{113}=34.47{\pm}0.07$이었다.