Calcium sulphate is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulphate causes permanent hardness in water.
| CAS | 7778-18-9 |
| Molecular Formula | Cas04 |
| Test | Specifications |
| Description | Calcium Sulphate occurs as a fine, white to slightly yellow white powder. It is anhydrous or contains two molecules of water of hydration. |
| Identification | Dissolve about 200 mg of sample by warming it with a mixture of 4 mL of 2.7 N hydrochloric acid and16 mL of water. A white precipitate forms when 5 mL of ammonium oxalate TS is added to 10 mL of the solution.
Upon the addition of barium chloride TS to the remaining 10mL, a white precipitate forms that is insoluble in hydrochloric and nitric acids. |
| Fluoride | Not more than 0.003% |
| Lead | Not more than 2 mg/kg |
| Loss in drying | Not more than 1.5 % |
| Selenium | Not more than 0.003% |
| Assay | Not less than 98.0% of Cas04 |
| Physical Appearance | White powder match against standard |
| pH 1% solution | 6.5 – 7.5 |
| Moisture content | 2% Max |
| Purity | 98% Min |
| Bulk density | 0.65 – 0.70 |
| Sieves test by 325 mesh | Free from black particles |
| Tile test | Free from black particles |
| Storage | Store in cool and dry place |
| Packaging | 25kg, 50kg |