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From Wikipedia

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.

There are broadly three types of decomposition reactions: thermal, electrolytic and catalytic.

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:

2H2O(I) → 2H2 + O2

Additional examples

An example of spontaneous decomposition is that of hydrogen peroxide, which will slowly decompose into water and oxygen:

2H2O2→ 2H2O + 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 metaloxide 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.

2MClO3→ 2MCl + 3O2

A common decomposition of a chlorate to evolve oxygen utilizes potassium chlorate as follows:

2KClO3→ 2KCl + 3O2

Many metal carbonates decompose to form metal oxides and carbon dioxide when heated.


Acetone peroxide

Acetone peroxide (triacetone triperoxide, peroxyacetone, TATP, TCAP) is an organic peroxide and a primaryhigh explosive. It takes the form of a white crystalline powder with a distinctive acrid odor.

It is susceptible to heat, friction, and shock. The instability is greatly altered by impurities. It is normally fairly stable when pure. It is not easily soluble in water. It is more stable and less sensitive when wet.

History

Acetone peroxide was discovered in 1895 by Richard Wolffenstein. He was the first chemist to use inorganic acids as catalysts. He was also the first researcher to receive a patent for using the peroxide as an explosive compound. In 1900 Bayer and Villiger described in the same journal the first synthesis of the dimer and also described use of acids for the synthesis of both peroxides. Information about these procedures including the relative proportions of monomer, dimer, and trimer is also available in an article by Milas and Golubović. Other sources include crystal structure and 3d analysis in The Chemistry of Peroxides edited by Saul Patai (pp. 396–7), as well as the Textbook of Practical Organic Chemistry by Vogel.

Chemistry

"Acetone peroxide" most commonly refers to the cyclictrimer TCAP (tri-cyclic acetone peroxide, or tri-cyclo, C9H18O6) obtained by a reaction between hydrogen peroxide and acetone in an acid-catalyzednucleophilic addition. The dimer (C6H12O4) and open monomer are also formed, but under proper conditions the cyclic trimer is the primary product. A tetrameric form was also described. In mildly acidic or neutral conditions, the reaction is much slower and produces more monomeric organic peroxide than the reaction with a strong acid catalyst. Due to significant strain of the chemical bonds in the dimer and especially the monomer, they are even more unstable than the trimer.

At room temperature, the trimeric form slowly sublimes, reforming as larger crystals of the same peroxide.

Acetone peroxide is notable as a high explosive not containing nitrogen. This is one reason why it has become popular with terrorists, as it can pass through scanners designed to detect nitrogenous explosives.

TCAP generally burns when ignited, unconfined, in quantities less than about 2 grams. More than 2 grams will usually detonate when ignited; smaller quantities might detonate when even slightly confined. Completely dry TCAP is much more prone to detonation than the fresh product still wetted with water or acetone. The oxidation that occurs when burning is:

2 C|9|H|18|O|6 + 21 O|2 → 18 H|2|O + 18 CO|2

Theoretical examination of the explosive decomposition of TCAP, in contrast, predicts in "formation of acetone and ozone as the main decomposition products and not the intuitively expected oxidation products." This result is in good agreement with the results of 60 years of the study of controlled decompositions in various organic peroxides. It is the rapid creation of gas from a solid that creates the explosion. Very little heat is created by the explosive decomposition of TCAP. Recent research describes TCAP decomposition as an entropic explosion.

The extreme shock, heat, and friction sensitivity are due to the instability of the molecule. Big crystals, found in older mixtures, are more dangerous, as they are easier to shatter—and initiate—than small ones.

Due to the cost and ease with which the precursors can be obtained, acetone peroxide can be manufactured by those without the resources needed to manufacture or buy more sophisticated explosives. When the reaction is carried out without proper equipment the risk of an accident is significant. Simply mixing sulfuric acid, hydrogen peroxide, and acetone can create the substance. The mixture starts as a liquid that quickly crystallizes into a powder.

There is a common myth that the only "safe" acetone peroxide is the trimer, made at low temperatures:

"The mixture must be kept below 10 degrees Celsius. If the crystals form at this temperature, it forms the isomer called tricycloacetone peroxide, which is relatively stable and safe to handle. If the crystals form above this temperature, the dimeric form, called dicycloacetone peroxide. This isomer is much more unstable, and could go off at the touch, making it not safe enough to be considered a practical explosive. As long as the temperature is kept below 10 degrees Celsius, then there is little to worry about."

The trimer is the more stable form, but not much more so than the dimer. All forms of acetone peroxide are sensitive to initiation. Organic peroxides are sensitive, dangerous explosives; due to their sensitivity they are rarely used by well funded militaries. Even for those who synthesize explosives as a hobby there are far safer explosives with syntheses nearly as simple as that of acetone peroxide. It is commonly combined with nitrocellulose by dissolving the nitrocellulose in acetone and then mixing


From Yahoo Answers

Question:I know that to calculate the rate constant I have to work out the rate equation, but I don't know how to work out the concentrations of yeast i used!!! i am varying the cocentration of yeast, and keeping the concentration of hydrogen peroxide the same. i used 5 ml of hydrogen peroxide (at 5 vol) then i used a yeast suspension of 4g/160 cm3, and diluted it to give different concentration solutions. the solutions were 100% 80% 60% 40% 20% i know that amount in mol+concentration x volume ARGH!! i need help. :(

Answers:You won't be able to express the yeast as a molar concentration because its a complex mixture. Because you've diluted a stock solution you know the relative concentrations so just use % or a dilution factor whatever is convenient.

Question:a) A sample of calcium carbonate is heated. b) Sulfur Dioxide gas is bubbled through water. c) Solid potassium oxide is added to a container of carbon dioxide gas. d) liquid hydrogen peroxide is warmed. e) Solid lithium oxide is added to water. f) molten aluminum chloride is electrolyzed. g) A pea sized piece of sodium is added to a container of iodine vapor. h) A sample of carbonic acid is heated. i) A sample of potassium chlorate is heated. j) Solid magnesium oxide is added to sulfur trioxide gas.

Answers:a) CaCO3 ~~> CaO + CO2 (Decomposition reactions usually produce simple salts and oxide gasses) b) SO2 + H2O ~~> H2SO3 (A nonmetal oxide in water will produce an acid) c) K2O + CO2 ~~> K2CO3 (CO2 + O ~~> CO3(2-)) d) 2 H2O2 ~~> 2 H2O + O2 (Decomposition reaction) e) Li2O + H2O ~~> 2(Li+) + 2(OH-) (A metal oxide in water will produce a base) f) 2 AlCl3 ~~> 2 Al(3+) + 3 Cl2 + 3e- (3 electrons are taken away from Al giving it its 3+ charge. The 3 electrons are given to the 3 Cl(1-) which converts them into a more stable form Cl2 gas. Al was oxidized and Cl was reduced.) g) 2Na + I2 ~~> 2 NaI (Na is oxidized and I is reduced) h) H2CO3 ~~> CO2 + H2O (Carbonic acid always decomposes into water and carbon dioxide) i) 2 KClO3 ~~> 2 KCl + 3 O2 (Decomposition reactions) j) MgO + SO3 ~~> MgSO4 (SO3 + O ~~> SO4(2-))

Question:What kind of chemical reactions can I make with 3% Hydrogen Peroxide? I need to make chemical reactions with 3%hydrogen peroxide. What chemicals can i mix with it?

Answers:bvlgarifitch92, Two easy ones (do it with pipettes of the peroxide, since it's pretty reactive: Drip it on a potato; it should fizz due to the decomposition of the peroxide by catalase in the potato; Drip it into a solution of bleach (sodium hypochlorite); it should produce bubbles due to the reaction that produces oxygen gas. Drip it onto a new (shiny) penny; the penny should tarnish due to oxidation of the copper. A crowd favorite: the iodine clock (see link below) I'll try to think of more (hope this is a good start)!

Question:If the optimum pH for catalase to react with hydrogen peroxide is 7, then why does the rate of reaction increase when a basic solution is added to the liver?

Answers:I just wanted to let you know that i'm in medical technology school, we learned all about this stuff and I have NO IDEA what the answer is. I'm looking it up in my books though. ... all i know is that changing the pH usually denatures or inhibits the enzyme. Maybe it somehow adds more substrate with the solution. Maybe the pH of the liver was more acidic to begin with, thus, adding the basic solution brought it closer to its optimum pH. I really don't have any hard facts, sorry i'm not much help.

From Youtube

decomposition of Hydrogen Peroxide :this is an example of of a catalyst speeding up a reaction. Yeast contains enzymes which are organic catalysts in this case break down hydrogen Peroxide which kills cells. When hydrogen peroxide decomposes or breaks down it separates in to H2O and O2 which are what the bubbles are filled with. Also heat is a by product of the reaction. There is a quite famous reaction called elephant's toothpaste which uses the same principle as the reaction except here a more power catalyst is used (usually potassium iodide) which creates a steaming colon of bubbles that shoots out of the container.

The Spirit Of Chemistry - Hydrogen Peroxide Decomposition :Just as my AP Chemistry Teacher, Mr. Robert Weiss did for me, I too on the first day of AP Chemistry release "The Spirit Of Chemistry" in a good luck (yet scientific) gesture. The reaction is performed with 30% hydrogen peroxide solution that has an amount of manganese dioxide added to it. The manganese dioxide only acts as a catalyst in the reaction, causing the rate of the decomposition of H2O2 to greatly increase. Oxygen gas is released from the "magic lamp". The reaction is exothermic, generating enough heat to cause the other product of the reaction, water, to escape as steam. This gives a great "genie from the bottle" effect. Hopefully the wishes of my AP Chemistry students shall be granted!