World Journal of Chemical Education
ISSN (Print): 2375-1665 ISSN (Online): 2375-1657 Website: Editor-in-chief: Prof. V. Jagannadham
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World Journal of Chemical Education. 2021, 9(3), 77-80
DOI: 10.12691/wjce-9-3-2
Open AccessArticle

Spectrophotometric Investigation of Complexation of Ferrous Ion with 3,5-Dintrosalicylic Acid

Gurvinder Kaur1, Sumanjeet Kaur1, Tribhuvan Kumar Pathak1, Vandana Sharma1, and Kartikay Tyagi1

1Department of Chemistry, SGTB Khalsa College, University of Delhi, Delhi, India

Pub. Date: September 07, 2021

Cite this paper:
Gurvinder Kaur, Sumanjeet Kaur, Tribhuvan Kumar Pathak, Vandana Sharma and Kartikay Tyagi. Spectrophotometric Investigation of Complexation of Ferrous Ion with 3,5-Dintrosalicylic Acid. World Journal of Chemical Education. 2021; 9(3):77-80. doi: 10.12691/wjce-9-3-2


The determination of stoichiometry and stability constant of metal-ligand complex holds great significance for chemical, physical, environmental and biological studies. In the present work, the stoichiometric ratio and stability constant of iron complex of 3,5-dinitrosalicylic acid was determined using Job’s method of continuous variation. Job’s method can be easily applied to investigate a wide range of colored complexes including mononuclear as well as polynuclear complexes of various species, therefore showing its usefulness for practical application in undergraduate University curriculum. The stoichiometry of the major complex formed was determined to have a 1:1 ratio of Fe+2 and 3,5-dinitrosalicylic acid. Stability constant value was determined and found to be 3 x 105. The resulting high stability of the complex can be attributed to resonance stabilization of metal-ligand П-bonding electron density. From the thermodynamic parameter, the negative value of overall change in Gibb’s free energy shows the complex formation between Fe+2 and 3,5-dinitrosalicylic acid is spontaneous and feasible.

absorption spectra stability constant stoichiometry 3,5-dinitrosalicylic acid continuous variation method transition metal complex

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[1]  Bent, H.E., French, C.L, “The structure of ferric thiocyanate and its dissociation constant in aqueous solution”,J. Am. Chem. Soc., 1941, 63(2), 568-572.
[2]  Harvey, A.E., Manning, D.L, “Spectrophotometric methods of establishing empirical formulas of colored complexes in solution”, J. Am. Chem. Soc., 1950, 72(10), 4488-4493.
[3]  Rose, N.J., Drago, R.S. “Molecular addition compounds of iodine. An absolute method for the spectroscopic determination of equilibrium constants”, J. Am. Chem. Soc., 1959, 81(23), 6138-6141.
[4]  Yoe, J.H., Jones, A. L., Colorimetric determination of iron with disodium-1,2-dihydroxybenzene-3,5-disulfonate”, Ind. Eng. Chem. Anal. Ed., 1944, 16(2), 111-115.
[5]  Job, P, “Formation and stability of inorganic complexes in solution”, Ann. Chim., 1928, 9, 113-203.
[6]  Holme, A., Langmyhr, F.R, “A modified and a new straight-line method for determining the composition of weak complexes of the form AmBn”, Anal. Chim. Acta., 1966, 36, 383-391.
[7]  Diehl, H., Lindstrom, F, Anal. Chem., “Eriochrome Black T and its calcium and magnesium derivatives” Anal. Chem. 1959,31(3), 414-418.
[8]  Miller, G.L, “Use of dinitrosalicylic acid reagent for determination of reducing sugar” Anal. Chem., 1959, 31(3), 426-428.
[9]  Dube, S.S., Dhindsa, S.S, J. Ind. Chem. Soc., 1969, 46, 838.
[10]  Dube, S.S., Dhindsa, S.S, “Potentiometric study on the composition and stability of beryllium complexes of 3,5-dinitrosalicylic acid” Z. Naturforsch, 1969, 24(8), 967-970.
[11]  Dube, S.S., Dhindsa, S.S, Naturforsch, “Potentiometric investigation on the 3,5-dinitrosalicyclic acid complex of Mg(II).” 1969, 24(10), 1234-1236.
[12]  Dube, S.S., Dhindsa, S.S, Indian, J. Chem., 1969, 7, 823.
[13]  Dube, S.S., Dhindsa, S.S, “Composition and stability of some bivalent transistion metal complexes of 3,5-dinitrosalicylic acid” Canad. J. Chem., 1970, 48, 1007-1010.
[14]  Inczedy, J. “Analytical applications of complex equilibria”. Ellis horwood series in analytical Chemistry. Wiley, New York, 1976.
[15]  Bosque-Sendra, J.M., almansa-Lopez, E., Garcia-Campana, A.M., Cuadros-Rodriguez, L, “Data Analysis in the determination of stoichiometries and stability constants of complexes” Anal. Sci., 2003, 19, 1431-1439.