- 関
- pyrolysis、pyrolytic、thermal cracking、thermal decomposition、thermolytic
WordNet
- transformation of a substance produced by the action of heat
- resulting from pyrolysis
PrepTutorEJDIC
- (有機化合物の)熱分解
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出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2014/02/09 21:04:50」(JST)
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- For the biological process, see decomposition.
Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes.
The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion.
Contents
- 1 Examples
- 1.1 Decomposition of nitrates, nitrites and ammonium compounds
- 2 Ease of decomposition
- 3 See also
- 4 References
Examples[edit]
- Calcium carbonate (limestone or chalk) decomposes into calcium oxide and carbon dioxide when heated. The chemical reaction is as follows:
-
- CaCO3 → CaO + CO2
- The reaction is used to make quick lime, which is an industrially important product.
Equipment used by Priestley in his experiments on gases
- Some oxides, especially of weakly electropositive metals decompose when heated to high enough temperatures. A classical example is the decomposition of mercuric oxide to give oxygen and mercury metal. The reaction was used by Joseph Priestley to prepare samples of gaseous oxygen for the first time, leading Antoine Lavoisier to explore the nature of the gas.
- Some foods will decompose exothermically at cooking temperatures; anyone who has overheated sugar or syrupy foods will know how long they take to cool. Mild versions of the process will produce caramelised dishes that are pleasant, but cannot be tasted safely before they have cooled to a comfortable temperature. Once they start to char, such dishes commonly will continue in a positive feedback loop; they become dangerously hot and continue to blacken from the inside out, and continue to produce smoke even well after being removed from the heat. In films, where stuntmen have to jump through breaking windows, the window panes traditionally were breakaway glass made of sugar, which is safer than real glass.[1][2] Melting the sugar is a tricky business, however; an error of just a few degrees will start a caramelisation process that will ruin the product, so nowadays suitable plastics are commonly used instead.[3]
- When water is heated to well over 2000 °C, a small percentage of it will decompose into its constituent elements:
-
- 2 H2O → 2 H2 + O2
- The compound with the highest known decomposition temperature is carbon monoxide at ≈3870 °C (≈7000 °F).[citation needed].
Decomposition of nitrates, nitrites and ammonium compounds[edit]
- Ammonium dichromate on heating yields nitrogen, water and chromium(III) oxide.
- Ammonium nitrate on strong heating yields dinitrogen oxide ("laughing gas") and water.
- Ammonium nitrite on heating yields nitrogen gas and water.
- Barium azide on heating yields barium metal and nitrogen gas.
- Sodium nitrate on heating yields sodium nitrite and oxygen gas.
Ease of decomposition[edit]
When metals are near the bottom of the reactivity series, their compounds generally decompose easily at high temperatures. This is because stronger bonds form between atoms towards the top of the reactivity series, and strong bonds break less easily. For example, copper is near the bottom of the reactivity series, and copper sulfate (CuSO4), begins to decompose at about 200°C, increasing rapidly at higher temperatures to about 560°C. In contrast potassium is near the top of the reactivity series, and potassium sulfate (K2SO4) does not decompose at its melting point of about 1069°C, nor even at its boiling point.[4]
See also[edit]
- Ellingham diagram
- Thermochemical cycle
- Thermal depolymerization
- Chemical thermodynamics
- Pyrolysis - thermolysis of organic material
References[edit]
- ^ Johnson, John J. J. Cheap Tricks and Class Acts: Special Effects, Makeup and Stunts from the Films of the Fantastic Fifties. Publisher: Mcfarland & Co 1995. ISBN 978-0786400935
- ^ "Inventions made to order" Popular Mechanics Vol. 73, No. 5. May 1940. Pages 696-699, 126A-127A
- ^ Kemmerer, Jack B. "TV Trickery" Popular Mechanics Vol. 109, No. 1 January 1958. Pages 127-129
- ^ Lide, David R. CRC Handbook of Chemistry and Physics, 90th Edition. Publisher: CRC Press 2009. ISBN 978-1420090840
UpToDate Contents
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English Journal
- Dipole relaxation in erythrocyte membrane: Involvement of spectrin skeleton.
- Ivanov IT, Paarvanova B, Slavov T.SourceDept. of Physics, Biophysics, Roentgenology and Radiology, Medical Faculty, Thracian University, Stara Zagora 6000, Bulgaria. Electronic address: ivanov_it@gbg.bg.
- Bioelectrochemistry (Amsterdam, Netherlands).Bioelectrochemistry.2012 Dec;88:148-55. doi: 10.1016/j.bioelechem.2012.03.005. Epub 2012 Mar 29.
- Polarization of spectrin-actin undermembrane skeleton of red blood cell (RBC) plasma membranes was studied by impedance spectroscopy. Relatedly, dielectric spectra of suspensions that contained RBCs of humans, mammals (bovine, horse, dog, cat) and birds (turkey, pigeon, duck), and human RBC ghost me
- PMID 22513264
- Preventing thermolysis: precursor design for volatile copper compounds.
- Coyle JP, Kurek A, Pallister PJ, Sirianni ER, Yap GP, Barry ST.SourceDepartment of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, Canada. sean_barry@carleton.ca.
- Chemical communications (Cambridge, England).Chem Commun (Camb).2012 Oct 28;48(84):10440-2. Epub 2012 Sep 19.
- A copper(i) iminopyrrolidinate was synthesized and evaluated by thermal gravimetric analysis (TGA), solution based (1)H NMR studies and surface chemistry to determine its thermal stability and decomposition mechanism. Copper(i) tert-butyl-imino-2,2-dimethylpyrrolidinate (1) demonstrated superior the
- PMID 22990169
Japanese Journal
- Photoelectrochemical Properties of Nanocrystalline Sb6O13, MgSb2O6, and ZnSb2O6-Based Electrodes for Dye-Sensitized Solar Cells
- Jang Jiyeon,Kim Seung-Joo
- Jpn J Appl Phys 51(10), 10NE23-10NE23-4, 2012-10-25
- … The preparation of Sb6O13 was based on thermolysis of a colloidal Sb2O5\Cdot4H2O suspension. …
- NAID 40019456873
- 熱分解制御法による多様なナノ粒子の大量合成 (ナノ構造の創製と応用)
- ディジタル・ヴァーサタイル・ディスク・レコーダブル用オキソノール色素の熱化学的性質の制御 : 高速記録時の熱的干渉の抑制
- 森嶌 慎一,割石 幸司,御子柴 尚 [他]
- Fuji Film research & development -(57) (-), 105-109, 2012-00-00
- NAID 40019349990
Related Links
- Thermolysis definition, Physiology. the dispersion of heat from the body. See more. Thesaurus Translator Reference Word of the Day Blog Slideshows Apps by Dictionary My Account Log Out Log In follow Dictionary.com More...
- thermolysis /ther·mol·y·sis/ (ther-mol´ĭ-sis) 1. chemical dissociation by means of heat. 2. dissipation of bodily heat by radiation, evaporation, etc.thermolyt´ic ther·mol·y·sis (th r-m l-s s) n. 1. Dissipation of heat from the body, as by ...
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