Ammonium paratungstate, APT for short, is a kind of white crystalline of flake or needle shape. Its chemical formula is (NH4) 10 (H2W12O42) • 4H2O. And the CAS No. is 11120-25- 5, 14311-52-5.
APT is insoluble in alcohol and is slightly soluble in water. Its solubility in water is less than 2% under the temperature of 20 °C. 
Ammonium paratungstate is usually in forms of pentahydrate and decahydrate. Chemical formula of pentahydrate is 5(NH4)2O•12WO3•5H2O. And chemical formula for decahydrate is 5(NH4)2O•12WO3•10H2O. Decahydrate is produced by evaporate tungstic acid. It will lose crystal water in dry air.
APT can be converted to AMT (Ammonium Metatungstate) as it is heated to 220 ~ 280 °C. At the time, it will lose part of the ammonia and water of crystallization. Heating to above 600 °C, APT can be completely converted to tungsten trioxide because it loses all ammonia and water of crystallization.
APT application:
1. As an industrial catalyst;
2. Used in the ceramic industry as a colorant;
3. As water absorbent gel in other areas;
4. Used as a reagent in laboratory;
5. As a source of high purity tungstic acid, tungsten metal powder or tungsten carbide.
More details, please visit:
http://www.tungsten-powder.com/what-is-ammonium-paratungstate.html
