| IUPAC name
| Other names
Glauber's salt (decahydrate)
Sal mirabilis (decahydrate)
|Molar mass|| 142.04 g/mol (anhydrous)|
322.20 g/mol (decahydrate)
|Density|| 2.664 g/cm3 (anhydrous)|
1.464 g/cm3 (decahydrate)
|Melting point|| 884 °C (1,623 °F; 1,157 K) (anhydrous)|
32.38 °C (90.28 °F; 305.53 K) (decahydrate) (decomposes)
|Boiling point||1,429 °C (2,604 °F; 1,702 K) (anhydrous)|
4.76 g/100 ml (0 °C)
13.9 g/100 ml (20 °C)
42.7 g/100 ml (100 °C)
19.5 g/100 ml (0 °C)
44 g/100 ml (20 °C)
|Solubility|| Soluble in glycerol, hydrogen iodide|
Insoluble in ethanol, halocarbons, hydrocarbons
|Vapor pressure||~0 mmHg|
|Safety data sheet|| Sigma-Aldrich (anhydrous)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Sodium sulfate, also known as Glauber's salt or sal mirabilis, is a chemical compound with the formula Na2SO4, useful for drying, more ofthen solvents and other liquids.
Sodium sulfate will react with carbon at high temperatures, to yield sodium sulfide:
- Na2SO4 + 2 C → Na2S + 2 CO2
Sodium sulfate is known to form double salts, such as alums, NaAl(SO4)2 (unstable above 39 °C) and NaCr(SO4)2 and even with other alkali metals, one example being Na2SO4·3K2SO4.
Aqueous solutions of sodium sulfate are pH neutral.
Sodium sulfate is a white deliquescent hygroscopic solid, poorly soluble in water (19.5 g/100 ml at 20 °C for anhydrous salt and 44 g/100 mL at 20 °C for decahydrate). It is insoluble in ethanol. Sodium sulfate has a density of 2.664 g/cm3 for the anhydrous form and 1.464 g/cm3 for the decahydrate. Its anhydrous form melts at 884 °C.
Sodium sulfate is available at pharmacies as Glauber's salt. Some products might also contain around 10% sodium bicarbonate. This can be removed by adding sulfuric acid or sodium bisulfite. In some countries, such as the Russian Federation, it is added into dry alkaline drain cleaners as a weak surfactant; it can be easily separated from the alkali, because the alkali in the drain cleaner is in form of large granules, and sal mirabilis a fine powder. Any household sieve or even dry gauze cloth will do the trick.
Sodium sulfate occurs naturally as the minerals thenardite (anhydrous Na2SO4) and mirabilite (Na2SO4·10H2O). Both forms appear depending on the weather conditions.
Sodium sulfate can be prepared by reacting a sodium salt or hydroxide with sulfuric acid or another soluble sulfate.
- Na2CO3 + H2SO4 → Na2SO4 + H2O + CO2
It can also be prepared by reacting sodium bisulfate with another sodium compound, such as sodium chloride. Because of its low solubility, sodium sulfate will precipitate. The resulting solid is filtered and dried to obtain the useful anhydrous form.
- Dry solvents
- Make sodium aluminium sulfate
- Electrolysis of water
- Thermal energy storage
- Sodium sulfide synthesis
Sodium sulfate is generally regarded as non-toxic, although its anhydrous form may cause irritations if touched or inhaled.
Anhydrous sodium sulfate should be stored in sealed bottles, in a dry place. The hydrated form doesn't require special storage.
Sodium sulfate can be poured down the drain, as long as it doesn't contain other toxic products.