Composition and Stability of Molybdenum (VI)-Quinalizarin Chelate

The formation of a pinkish violet chelate between hexavalent molybdenum and quinalizarin has been studied in 50% ethanolic medium. The chelate has maximum absorbance at 520 nm. The chelate is stable in the \(p\)H range 3 to 6·5. The composition has been studied by three different methods and has been found that one mole of molybdenum reacts with one mole of quinalizarin to form a complex. The stability constant was found by the method of Banerji and Dey and mole ratio method. The values of log lc in 50% ethanolic medium by above two methods are 4·11±0·16 and 4·84±0·00 respectively at 25° and at 5·0± 0·1 \(p\)H. The average value of free energy of formation calculated from the above two values of log \(k\) is -6·07±0·12 K.cal.