Difference Between White Tungstic Acid and Yellow Tungstic Acid
White tungstic acid and yellow tungstic acid difference mainly embodies in their appearance, white tungstic is white powder with white microcrystalline structure, yellow tungstic acid is the most common seen tungstic acid, color is light yellow and is in powder form.
Difference in Property
White tungstic acid and yellow tungstic acid is different in physical and chemical property. Content of yellow tungstic acid will be different along with the changes of producing conditions. When content is WO3.H2O, its relative density is 5.5g/cm3, dehydrate in 100℃, insoluble in water, will retrogradation after dipping, soluble in ammonia solution, alkali solution and high concentrate hydrochloric acid. White tungstic acid has apparent activity, optical sensitivity and can be easy reduced. Besides that, white tungstic acid fresh produced can easily dissolve in phosphorus acid, yellow tungstic acid will not.
Difference in Producing Method
1.Yellow tungstic acid can be produced by reacting between Na2WO4•2H2O solution and HCl, and turns into sodium polytungstate. Then add in overdosed high concentration hydrochloric acid. The yellow tungstic acid produced by this method has sodium impurity. In recent years, it is gradually replaced by ion exchange method and solvent extraction method.
2.White tungstic acid can be produced by adding sodium tungstate solution and dilute nitric acid.
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