Barium peroxide: characteristics, formula, properties

He Barium peroxide , Also called"barium peroxide"or"barium dioxide", is an inorganic compound having the formula BaO 2. This white, gray-looking solid when impure is one of the most common inorganic peroxides and was the first peroxide compound to be discovered.

Among its properties is that of being an oxidizing agent, and giving a bright green color when burned - as do all barium compounds -, so it is often common to find it in fireworks. Formerly used as precursor of hydrogen peroxide, from the reaction between barium peroxide octahydrate plus water. It is also odorless.

Barium peroxide: characteristics, formula, properties Fig. 1. Appearance of barium peroxide. By Ondřej Mangl (Own work), via Wikimedia Commons.

When it is the union of a metal, with a nonmetal, its bond is predominantly ionic, reason why it will have the properties that this type of bond attributes to them.


The barium peroxide formula is BaO 2 , So that it is the combination of an alkaline earth metal - barium - that will act with valence +2, and of a nonmetallic element such as oxygen, which will act with valence -2. The units of barium peroxide are arranged in the space acquiring a tetragonal structure.

Barium Peroxide: Characteristics, Formula, Properties 1 Fig. 2. Tetragonal structure in space. By Quatrostein (Own work) [GFDL ( or CC BY-SA 3.0 (], Via Wikimedia Commons

Properties and characteristics

Being a peroxide contains two subunits of O2~², and when it is in its solid form, it is isomorphic to calcium carbide or calcium CaC 2 .

It shows poor solubility in water (Paez Muñoz, nd) (solubility = 15 g / L at 0 ° C, 0.091 g / 100 mL at 20 ° C, when octahydrated), and decomposes when heated above 800 ° C, Of barium - BaO- and molecular oxygen - O 2 -. It is able to hydrolyze in water slightly, giving barium hydroxide - Ba (OH) 2 - and hydrogen peroxide - H 2 OR 2 -. Its oxidizing power, makes it capable of oxidizing Fe 2+ To faith 3+ .

Other features to highlight

  • Molecular mass : 169.33 g / mol when anhydrous, and 313.45 g / mol when octahydrate is found.
  • Appearance : White to grayish when it is anhydrous (see Fig. 1), and colorless solid when octahydrated.
  • Melting and boiling points : 450 º C and 800 º C respectively.

Seeing the data of the compound (PubChem, 2016), it is observed that this decomposes when heated, and also on contact with water and acids, producing oxygen and hydrogen peroxide, which increases the risk of fire.

In addition to the characteristic of being a strong oxidizer, it reacts violently with combustible and reducing materials. Contact with water of this substance can produce a reaction temperature and a concentration of oxygen high enough for the organic materials to combust.

It also reacts explosively with anhydrous acetic acid (CAMEO Chemicals, 2016), due to the formation of acetyl peroxide. It burns when mixed with aluminum powder or carbon-silicon alloys. The wood can also burn if rubbed with this peroxide. It also forms highly reactive mixtures with materials that are combustible.


To obtain metal peroxides, the reaction of the corresponding oxide is usually carried out with hydrogen peroxide in the corresponding solvent.

In the case of barium peroxide, it is no exception, and a reversible reaction of the barium oxide with molecular oxygen takes place, so that the peroxide forms around 500 ° C, and oxygen is released from the 820 ° C.

This reaction of synthesis, was the basis for the production of oxygen in the well-known"Brin Process". The reaction that was discovered by Joseph-Louis Gay-Lussac, and in 1811, scientists Louis-Jacques Thenards and Jean-Baptiste Boussingault, attempted to use this reaction to obtain a process from which oxygen could be produced. The process was useful in a couple of cycles, but later became inefficient.

Other compounds such as sodium peroxide Na 2 O, and SrO strontium oxide, have similar behaviors, to barium peroxide.

One of the applications for which barium peroxide was used is to obtain hydrogen peroxide through the following reaction:

Barium sulphate - is an insoluble compound, which can be separated from the reaction mixture by filtration, and thus obtain the hydrogen peroxide.

It is also used as previously mentioned, as an oxidizing agent, but as a toxic product, because when it is inhaled it causes irritation to the mucous membranes, neck and nose, its contact with the eyes or skin can cause severe burns.

Ingestion causes excessive salivation, vomiting, colic, diarrhea, convulsive tremors, acceleration of the pulse, high blood pressure, hemorrhages, etc., besides damaging intestines, kidneys and even muscle paralysis. Its use is very limited, including those uses to which other peroxides are commonly used, such as bleach and disinfectant.

Also used (New Jersey Department of Health and Senior Services, 2001) in aluminum welds, and in the dyeing of some textiles.


  1. CAMEO Chemicals. (2016). BARIUM PEROXIDE | NOAA. Retrieved January 9, 2017, from
  2. New Jersey Department of Health and Senior Services. (2001). Barium peroxide. Hazardous Substance Fact Sheet .
  3. Paez Muñoz, A. (n.d.). Practice 1: Alkaline and alkaline earth metals. Retrieved January 9, 2017, from
  4. PubChem. (2016). BARIUM PEROXIDE | BaO2. Retrieved January 9, 2017, from
  5. Royal Society of Chemistry. (2016). Substance: Barium peroxide - Learn Chemistry Wiki. Retrieved January 9, 2017, from