CASR |
: | 7681-57-4 |
Molecular Formula |
: | Na2S2O5 |
Molecular Weight |
: | 190.1 |
| Specifications | |
|---|---|
| Description: | Colourless, prismatic crystals or a white or creamy white powder; odour, sulphurous. |
| Solubility: | Freely soluble in water; slightly soluble in ethanol (95%) |
| Identification A (Reaction of Sodium): | A dense white precipitate should form. |
| Identification B (Reaction of sulfates): | White precipitate should form. |
| pH: | 3.5 to 5.0 |
| Arsenic (As): | NMT 4 ppm |
| Heavy metals: | NMT 20 ppm |
| Iron (Fe): | NMT 40 ppm |
| Thiosulphate: | Not more than a faint opalescence should produced. |
| Assay: | 95.0% - 100.5% |
