eng Ansari Education and Research Society Journal of Ultra Chemistry 0973-3450 2319-8036 August 2009 5 2 259 264 juc 716 article K. S. Parikh (ksparikh64@yahoo.co.in) 1 R. M. Patel 2 K. N. Patel 2 Department of Chemistry, Sheth M.N. Science College, North Gujarat, Patan - 384265 (INDIA) Shri U.P. Arts. Smt. M.G. Panchal Science and Shri V.I. Shah Commerce College, Pilvai - 382 850 (INDIA) <p style="text-align: justify;"><br /> A simple, sensitive and specific spectrophotometric method has been developed for the determination of manganese (II) in benzene. The metal ion reacts with 2-hydroxy-4-n-butoxy-5-bromo propiophenone thiosemicarbazone (HBBrPT) forming a dark yellow coloured complex in the pH range 7.0-11.0. The complex shows maximum absorption at 440 nm. Beer&#39;s law is obeyed in the range 2.74-6.86 &micro;g/ml. The molar absorptivity and Sandell&#39;s sensitivity are found to be 5229 l mol^-1 cm^-1 and 0.0105 &micro;g cm^-2, respectively. The solid complex have been isolated and characterized on the basis of elemental analysis, UV, IR, NMR and Mass spectra. HBBrPT is found to be a selective and strong chelating agent for manganese. The results deduced from Job&#39;s method of continuous variation, the mole ratio and the slope ratio method showed that metal: ligand ratio in the complex to be 1:2. The stability constant of the complex found to be 1.92 X 10⁷. The free energy change for the complex formation reaction is found to be -10.158 K cal/mole at 32^oC. The complex is fairly stable for about 24 h and up to 55^oC.</p> https://journalofchemistry.org/paper/716/ 2-hydroxy-4-n-butoxy-5-bromo propiophenone Spectrophotometric determination spectral study foreign ion