Tungstic Acid Appearance Yellow Free Flowing Powder Formula H2WO4 CAS NO 7783-03-1 Molecular Weight 249.853 g/mol. Assay 99% – 100% pH 4 and above Solubility 10% solution is clear in dilute 25% ammonia solution. Insoluble less than 0.2% Iron Less than 50PPM Application Catalysts, Tungsten Metal Contact Us Enquire Now