Selenium Dioxide Cas no.7446-08-4 Molecular Weight: 110.96 Chemical Formula: SeO2 Appearance: White, glittering squared crystal Content: 98%min. Cu: 0.002% max. Ni: 0.002% max Co: 0.001% max. S: 0.03% max. Insoluble matter in water: 0.2%max. Selenium Dioxide is prepared by oxidation of Selenium by burning in air, nitric acid or by reaction with Hydrogen Peroxide, but perhaps the most convenient preparation is by the dehydration of Selenous Acid. Package: 25KG/fibre drum or iron drum, lined with plastic bag.