Sodium Dicromate
Sodium dichromate is the inorganic compound with the formula Na2Cr2O7. Usually, however, the salt is handled as its dihydrate Na2Cr2O7·2H2O. Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compounds and materials based on chromium are prepared from this salt.[1] In terms of reactivity and appearance, sodium dichromate and potassium dichromate are very similar. The sodium salt is, however, around twenty times more soluble in water than the potassium salt (49 g/L at 0 °C) and its equivalent weight is also lower, which is often desirable.
| Chemical formula | Na2Cr2O7 |
| Molar mass | 261.97 g/mol (anhydrous),298.00 g/mol (dihydrate) |
| Appearance | bright orange |
| Odor | odorless |
| Density | 2.52 g/cm3 |
| Melting point | 356.7 °C (674.1 °F; 629.8 K) |
| Boiling point | 400 °C (752 °F; 673 K) decomposes |
| Solubility in water | 73 g/100 mL at 25 °C |
| Solubility in other solvents | soluble in methanol, ethanol |
| Vapor pressure | 0.4 mmHg (20 °C)[3] |
| Refractive index | 1.661 (dihydrate) |