Difference between revisions of "Sodium sulfate"

Revision as of 11:55, 4 August 2015

Sodium sulfate, also known as Glauber's salt or sal mirabilis, is a chemical compound with the formula Na₂SO₄, useful for drying.

Properties

Chemical

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.

Physical

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.

Availability

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.

Sodium sulfate occurs naturally as the minerals thenardite (anhydrous Na₂SO₄) and mirabilite (Na₂SO₄·10H₂O). Both forms appear depending on the weather conditions.

Preparation

Sodium sulfate can be prepared by reacting a sodium salt or hydroxide with sulfuric acid or another soluble sulfate. It can also be prepared by reacting sodium bisulfite with another sodium compound, such as sodium chloride.

Projects

• Desiccator
• Dry solvents
• Make sodium aluminium sulfate
• Electrolysis of water
• Thermal energy storage
• Sodium sulfide synthesis

Handling

Safety

Sodium sulfate is generally regarded as non-toxic, although its anhydrous form may cause irritations if touched or inhaled.

Storage

Anhydrous sodium sulfate should be stored in sealed bottles, in a dry place. The hydrated form doesn't require special storage.

Disposal

Sodium sulfate can be poured down the drain, as long as it doesn't contain other toxic products.

References

Relevant Sciencemadness threads

• Manufacturing of sodium sulfate from “salt cake”
• Extraction of sodium sulfate from powder detergent
• Niche uses for Sodium Sulfate?