Calcium peroxide or calcium dioxide is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula CaO₂. It is the peroxide (O₂²⁻) salt of Ca²⁺. Commercial samples can be yellowish, but the pure compound is white. It is almost insoluble in water.

Structure and stability

As a solid, it is relatively stable against decomposition. In contact with water however it hydrolyzes with release of oxygen. Upon treatment with an

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

, it forms hydrogen peroxide.

Preparation

Calcium peroxide is produced by combining calcium salts and hydrogen peroxide: :Ca(OH)₂ + H₂O₂ → CaO₂ + 2 H₂O The octahydrate precipitates upon the reaction of

calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has m ...

with dilute hydrogen peroxide. Upon heating it dehydrates.

Applications

It is mainly used as an oxidant to enhance the extraction of precious metals from their ores. In its second main application, it is used as a

food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...

under the

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E930 it is used as flour bleaching agent and

improving agent A dough conditioner, flour treatment agent, improving agent or bread improver is any ingredient or chemical added to bread dough to strengthen its texture or otherwise improve it in some way. Dough conditioners may include enzymes, yeast nutrients ...

. In agriculture it is used in the presowing treatments of rice seed. Also, calcium peroxide has found use in

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

to oxygenate and disinfect water. In the ecological restoration industry it is used in the treatment of soils. Calcium peroxide is used in a similar manner to magnesium peroxide for environmental restoration programs. It is used to restore soil and groundwater contaminated with petroleum by the process of enhanced in-situ bioremediation. It is a minor component of some dentifrices. It is also used for curing polythioether polymers by oxidising terminal thiol groups to disulphide bridges.

References

{{DEFAULTSORT:Calcium Peroxide Peroxides Calcium compounds Food additives Bleaches Disinfectants Oxidizing agents