Difference between revisions of "Sodium peroxide"
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| − | Anhydrous sodium peroxide reacts with water. Part of it is hydrolyzed irreversibly into [[oxygen]], [[sodium hydroxide]] and [[water]]. Part is converted into the hydrate, which undergoes reversible hydrolysis and can be crystallized out of the solution by adding [[ethanol]]. The octahydrate is soluble in water without decomposition. | + | Anhydrous sodium peroxide reacts with water. Part of it is hydrolyzed irreversibly into [[oxygen]], [[sodium hydroxide]] and [[water]]. Part is converted into the hydrate, which undergoes reversible hydrolysis and can be crystallized out of the solution by adding [[ethanol]]. The irreversible reaction with water is actually caused by heat generated by common dissolution of sodium peroxide, and low temperatures suppress it: it is possible to dissolve anhydrous sodium peroxide in ice-cold water without much loss to decomposition. The octahydrate is soluble in water without decomposition. |
It reacts with [[carbon dioxide]] to produce oxygen and [[sodium carbonate]]. | It reacts with [[carbon dioxide]] to produce oxygen and [[sodium carbonate]]. | ||
Revision as of 07:12, 14 June 2016
Sodium peroxide is a sodium salt of hydrogen peroxide. Its formula is Na2O2. It is somewhat unstable and a strong oxidizer.
Contents
Properties
Physical
Sodium peroxide exists in two main forms: anhydrous and octahydrate (Na2O2·8H2O). Other lesser known hydrates also exist, but they have little importance.
Anhydrous sodium peroxide is a yellow powder (white if very high-grade: the yellow color is caused by contamination with sodium superoxide). The octahydrate appears as colorless crystals with a low melting point (30 Celsius).
Chemical
Anhydrous sodium peroxide reacts with water. Part of it is hydrolyzed irreversibly into oxygen, sodium hydroxide and water. Part is converted into the hydrate, which undergoes reversible hydrolysis and can be crystallized out of the solution by adding ethanol. The irreversible reaction with water is actually caused by heat generated by common dissolution of sodium peroxide, and low temperatures suppress it: it is possible to dissolve anhydrous sodium peroxide in ice-cold water without much loss to decomposition. The octahydrate is soluble in water without decomposition.
It reacts with carbon dioxide to produce oxygen and sodium carbonate.
Attempts to calcine the octahydrate result in its decomposition, the crystals turn into sodium hydroxide. There is no easily available way to turn the octahydrate into the anhydrous salt, but there were reports that putting it in a desiccator with very concentrated (98%) sulfuric acid for a long time does the trick.
Availability
Sodium peroxide, usually anhydrous, is commonly sold by various chemical suppliers.
Preparation
Anhydrous sodium peroxide is usually prepared by burning sodium metal in air or in a gentle stream of oxygen. The octahydrate can be easily prepared by a simple neutralization reaction with hydrogen peroxide (a weak acid) and sodium hydroxide. The crystals can be displaced out of solution with ethanol.
Handling
Safety
Avoid contact of anhydrous sodium peroxide with organic solvents. This may result in fire or explosions.
Sodium peroxide will cause burns on contact with bare skin.
Storage
Anhydrous sodium peroxide should be kept in a tightly closed jar, to avoid contact with water vapor. The octahydrate should be kept in a cold place, also in a closed jar.
Disposal
Any form of sodium peroxide can be neutralized by adding any acid and manganese dioxide. This reduces the compound to a sodium salt of that acid and oxygen.
