Abstract

Salah M. Sultan, S. A. Al-Tamrah, I. Z. Al-Zamil and A. M. Aziz-Al-Rahman

The complex formed between molybdenum (V) and thiocyanate has been studied spectrophotometrically in sulphuric, hydrochloric, perchloric and nitric acid media. It was found to be highly unstable especially in perchloric and nitric acids. The formation of a series of complexes was suggested but no strong evidence could be offered, A complex of Mo:SCN ratio el 1.00:1,00 mm observed and found to be stable only in the range of 2.35 to 2.70 M H2SO4. and 0.80 to 1.20 M HCI, that absorbs at 427 nm and 423 nm in these two acids respectively. Formation constant and molar absorbtivity of the 1:1 complex were calculated and an interpretation for the change of absorbance in two ranges of the acid concentration was offered. It is now recommended that the use of thiocyanate for the precise determination of molybdenum it ill aboised.

Stability; Molybdenum

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