Chemical decomposition
Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction. The stability that a chemical compound ordinarily has is eventually limited when exposed to extreme environmental conditions like heat, radiation, humidity or the acidity of a solvent. The details of decomposition processes are generally not well defined, as a molecule may break up into a host of smaller fragments. Chemical decomposition is exploited in several analytical techniques, notably mass spectrometry, traditional gravimetric analysis, and thermogravimetric analysis.
A broader definition of the term decomposition also includes the breakdown of one phase into two or more phases.[1]
There are three broad types of decomposition reactions: thermal, electrolytic and catalytic.[citation needed]
Reaction formula
The generalized reaction for chemical decomposition is:
- AB → A + B with a specific example being the electrolysis of water to gaseous hydrogen and oxygen:
- 2 H2O(I) → 2 H2 + O2
Additional examples
An example of spontaneous decomposition is that of hydrogen peroxide, which will slowly decompose into water and oxygen:
- 2 H2O2 → 2 H2O + O2
Carbonates will decompose when heated, a notable exception being that of carbonic acid, H2CO3. Carbonic acid, the "fizz" in sodas, pop cans and other carbonated beverages, will decompose over time (spontaneously) into carbon dioxide and water
- H2CO3 → H2O + CO2
Other carbonates will decompose when heated producing the corresponding metal oxide and carbon dioxide. In the following equation M represents a metal:
- MCO3 → MO + CO2
A specific example of this involving calcium carbonate:
- CaCO3 → CaO + CO2
Metal chlorates also decompose when heated. A metal chloride and oxygen gas are the products.
- 2 MClO3 → 2 MCl + 3 O2
A common decomposition of a chlorate to evolve oxygen utilizes potassium chlorate as follows:
- 2 KClO3 → 2 KCl + 3 O2
See also
References
- ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "decomposition". doi:10.1351/goldbook.C01020
External links
