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10 Examples of Decomposition Reactions

A chemical reaction represents the conversion of reactants to product molecules. A chemical reaction can involve combination, synthesis, decomposition, or oxidation-reduction of reactant molecules. 
A decomposition reaction is also known as analysis reaction which is one of the most common chemical reactions out of all reactions. These reactions involve the decomposition or cleavage of reactant molecules to form small product molecules. 

The general decomposition reaction can be written as given below;
AB → A + B
For example; the electrolysis of water results the formation of oxygen and hydrogen gas involves the decomposition;
2 H2O → 2 H2 + O2
Similarly the decomposition of solid potassium chloride results the formation of solid potassium with gaseous chlorine molecule. 
The chemical reaction can be written as given below;
2 KCl(s) → 2 K(s) + Cl2(g)

Overall it is a type of chemical reaction which can be defined as the reaction which involves the splitting of a single compound into two or more simple substances under certain reaction conditions. 
We can consider it as the opposite reaction of the combination reaction. A combination reaction involves the combination of two or more simple substances to form a new bigger chemical substance. 
The digestion of food in human body is also an example of decomposition reaction in which the major constituent parts of food materials such as carbohydrates; fats etc. decompose to form simple compounds with a certain amount of energy. 
This energy is used in other metabolic activities of living bodies. Such types of reactions can be classified as thermal, electrolytic, and photo decomposition reaction. 
The thermal decomposition reaction is also known as thermolysis in which a single substance decomposes into 2 or more parts to form simple substance in the presence of heat. 

Such reactions are endothermic in nature as they require some heat to cleave the chemical bonds found in the chemical substance. 
For example; the decomposition of CaCO3 results the formation of CaO (calcium oxide) and CO2 (carbon dioxide) at high temperature. 
The reaction can be written as given below;
CaCO3(s) --> CaO(s) + CO2(g)
Similarly the decomposition of potassium chlorate (KClO3) at high temperature results the formation of solid potassium chloride and oxygen gas. Same reaction is used for the preparation of oxygen gas.

2KClO3(s) --> 2KCl (s) + 3O2(g)
This reaction can be carried out in the presence of catalyst MnO2 at low temperature. 
The decomposition of ferric hydroxide at high temperature results the formation of ferric oxide with water. 
Similarly the thermal decomposition of hydrated oxalic acid removes the water content from molecule to form anhydrous oxalic acid.

(COOH)2. 2H2O --> (COOH)2 + 2H2O
Another type of decomposition is electrolytic decomposition which is also known as electrolysis. 
This reaction takes place in presence of electric current in the aqueous solution of the sample. The electrolysis of water is the best example of electrolysis. 
The decomposition takes place by passing electric current through it. The reaction can be written as given below;
2H2O (l) --> 2H2(g) + O2(g)
Metallic salts such as sodium chloride can also electrolyzed to form molten sodium with chlorine gas on passing electricity in the molten sodium chloride. 
The photolysis or photo decomposition reaction involves the cleavage of given chemical compound in the presence of light. 

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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.

Organic Reactions

Organic Reactions is a secondary reference which synthesizes the organic chemistry literature around particular chemical transformations. Each chapter of Organic Reactions is devoted to a particular organic chemical reaction, and chapters provide exhaustive coverage of literature work in the form of a tabular survey of known reactions. Mechanistic and experimental details, including the scope and limitations of each transformation, are also included.

Organic Reactions is a comprehensive reference work that contains authoritative, critical reviews of many important synthetic reactions. Authors for these chapters are solicited by the board of editors from leading chemists worldwide. The publication process entails a thorough peer-review process, ensuring the high quality and attention to detail for which this series is noted. Organic Reactions chapters focus primarily on the preparative aspects of a given transformation. Particular attention is paid to substrate scope, reaction limitations, stereochemical aspects, effects of chemical structures, and the selection of experimental conditions. Detailed procedures illustrating the significant modifications of the chemical reaction are also included, along with comparisons to other methods to achieve a similar transformation. Every chapter contains a comprehensive compilation all of the published examples of the reaction organized in tables according to the structure of the starting material. Each reaction is presented with information about the reaction conditions, yield, products, and is fully referenced.


The aim of Organic Reactions since its initial publication in 1942 has been to assist organic chemists in the design of new experiments by providing "critical discussions of the more important synthetic reactions." Organic Reactions is unique in providing an authoritative discussion of the topic reaction accompanied by tables that organize all published examples of the reaction being reviewed. This combination of critical discussion and thorough coverage is responsible for the leading position this series occupies for scientists interested in the reactions of organic chemistry. An additional distinctive feature of this series is that it is assembled almost entirely through voluntary dedicated efforts of its authors, editors and assistants.

The Organic Reactions book series is owned and copyrighted by Organic Reactions, Inc. a not-for-profit, private operating foundation incorporated in the state of Illinois. The books are published by John Wiley and Sons, Inc. who also manage and maintain the [http://onlinelibrary.wiley.com/book/10.1002/0471264180 Organic Reactions website].


The decision to undertake the preparation and presentation of "critical discussions of the more important (synthetic) reactions" was made at a meeting of the editors of Organic Syntheses and representatives of John Wiley & Sons during the Eighth National Organic Chemistry Symposium at St. Louis in December 1939. At that meeting the organizational setup was agreed upon, the operating procedures were roughed out, and the topics and authors were selected for Volume 1. These actions were formalized by the incorporation of Organic Reactions in Illinois on August 1, 1942, for educational and research purposes, with Roger Adams, Harold R. Snyder, Werner E. Bachmann, John R. Johnson, and Louis F. Fieser as directors, and by the appearance later that year of Volume 1. Roger Adams was elected president and served as President and Editor-in-Chief until he was succeeded in both positions by Arthur C. Cope in 1960 with the publication of Volume 11. He remained an active member of the Editorial Board until his death in 1971. Professor Cope in turn was succeeded in 1966 by Professor William G. Dauben who served from 1966-1984. Subsequent Editors-in-Chief and Presidents of the corporation are: Professor Andrew S. Kende (1984–1988), Professor Leo A. Paquette (1988–2000) Professor Larry E. Overman (2000–2007) and Professor Scott E. Denmark (2008–present). The close relationship of Organic Reactions to Organic Syntheses, Roger Adams, and John Wiley & Sons is obvious; the great value of that relationship is equally obvious to all who have been connected with the series as editors and authors.

From Yahoo Answers

Question:The following is an example of reactions involving heterogeneous catalysts: the decomposition og phosphine (PH3) over tungsten (W) (a solid catalyst): 4PH3(g) -> P4(g) + 6H2(g) The rate of the above reaction is found to be independent of the pressure of PH3 as long as the pressure of PH3 is sufficiently high (say >= 1 atm). Explain.

Answers:Lancenigo di Villorba (TV), Italy LET ME RECOVER THE EXPERIMENTAL FACTs, HENCE I SHOW MY REASONINGs. EXPERIMENTAL FACTs Phosphine undergoes decomposition in Its Chemical Elements if it flows upon a TUNGSTEN-BASED powder which is able to acts as a CATALYST : meanwhile TUNGSTEN maintain its chemical nature, it enhances the Decomposition's Rate which runs VERY FASTER THAN when Catalyst there wasn't. If the Partial Pressure of Phosphine results GREATER THAN a THRESHOLD VALUE, Kinetic Data show a Decomposition's Rate iniflunced by Partial Pressure. DISCUSSION The mechanism related to this Decomposition experiment involves FIVE MAIN STEPs, as the following ones : -) Phosphine must diffuse from Gas Bulk toward the TUNGSTEN's surface ; -) Phosphine interact with Tungsten's surface, e.g. Tungsten ADSORBs Phosphine ; -) Adsorbed Phosphine forms Secundary Chemical Bonds with Tungsten, so the Decomposition take place giving Phosphorus Atoms and Hydrogen Ones in the BOUND FORM TO TUNGSTEN ; -) Phosphorus and Hydrogen's BOUND FORMs break its Chemical Bonds ; -) Phosphorus and Hydrogen diffuse outward. RATE DETERMINING STEP's approach assumes that the Decomposition's Rate results EQUAL THAN the Lowest's One among Its Five Elementar Step's Rates. In particular way, ii) STEP is related to ISOTHERMAL BEHAVIOUR of ADSORPTION, e.g. it states that it exists a THRESHOLD VALUE of Gas Molarity leading the Adsorption Equilibria to Its Maximum's Values. I hope this helps you.

Question:At 800 K, the following data is obtained: Reactant Concentration Rate of decomposition of CH3CHO (CH3CHO) (M) -d(CH3CHO)/dt(Ms-1) 0.100 9.0 * 10^ -7 0.200 36 * 10^ -7 0.400 14.4 * 10^ -6 a. write the rate equation for the reaction b. what is the order of the reaction c. calculate the rate constant for the reaction at 800K d. calculate the decomposition rate at 800K at the instant when (CH3CHO)= 0.250 Please help I have no idea how to do this

Answers:a. Rate of simple reactions depends only on reactant concentration(s). So the rate law of this reaction should have the form rate = - d[CH CHO]/dt = k [CH CHO] That means rate of reaction is proportional to the n-th power of reactant concentration. To find n compare two experiments. From 1st to 2nd experiment concentration is doubled, which quadruples the rate. The same is if you compare 2nd and 3rd experiment. Comparing 1st and 3rd run you find quadrupling concentration leads to sixteen-fold rate of reaction. All this indicates that rate is proportional to the squared concentration of acetalhyde, i.e. n=2 Hence the rate equation of this reaction is rate = -d[CH CHO]/dt = k [CH CHO] b. n=2 is the order of reaction with respect to acetaldehyde. The overall order of reaction is the sum of the exponents of all reactant concentrations occurring in rate equation. Here we have only one reactant, that means overall order and order with respect to that reactant are the same. So the answer is second order. c. Just take the result from one experiment and substitute to rate equation and solve for k: e.g 1st experiment -d[CH CHO]/dt = k [CH CHO] => k = -d[CH CHO]/dt / [CH CHO] = 9.0 10 Ms / (0.10M) = 9.0 10 M s d. -d[CH CHO]/dt = k [CH CHO] = 9.0 10 M s (0.250M) = 56.25 10 Ms

Question:In my Grade 10 Science course, there is a question that I have to base a whole project around or I don't get my credit. The question is: "Research and list an example from everyday life for each of the five types of chemical reactions." the 5 types of chemical reactions are (if I remember correctly) Synthesis, Decomposition, Combustion, Single Displacement, Double Displacement. I need an example of each of those types of reactions that relate to everyday life. I think that NaCl (table salt) is a Synthesis because it's Na Cl -> NaCl right? But I need some examples from everyday life for all the others please. Thanks in advance.

Answers:Your 10th grade chemistry class probably won't really give you the correct names of all the reaction types, but those are basically it. There are also lots more reaction types, but you won't cover those until later. Your 10th grade chemistry class will be filled with half-truths and broad horrible generalizations, but at least you will be exposed to chemistry. Na^+ + Cl^- --> NaCl is true, and would fall under synthesis reactions. A (formerly?) common decomposition reaction would be sodium bicarbonate's reaction that puts out fires (in fire extinguishers): 2NaHCO3 --> Na2CO3 + H2O + CO2. It is effective at putting out fires because of the CO2 blocking Oxygen getting to the fire, the H2O absorbing some of the heat, and then there is the fact that the reaction itself is endothermic, or that when it happens the area around gets a little colder. Combustion is a very common reaction - it's what makes our cars go, and it's what burning is. Basically it's something containing carbon reacts with oxygen to form CO2 and H2O. Here's a simple example of the combustion of Methane, a common "natural gas": CH4 + 2O2 --> CO2 + 2H2O There's no such "Single Displacement reaction" in my vocabulary. The closes thing I can think of would be an aqueous redox reaction: Mg + 2AgNO3 (silver nitrate) --> Mg(NO3)2 (magnesium nitrate) + 2Ag A "double displacement reaction" is actually called a metathesis reaction. It is a common reaction in aqueous salts: NaCl + AgNO3 --> NaNO3 + AgCl (this one is cool because AgCl is insoluble, so it's like putting two liquids together and getting a solid out of it).

Question:i need an example of each of the following chemical reaction types that are used in our daily lives, single replacement, double, decomposition, synthesis and combustion. THANX ASAP ASAP ASAP ASAP ASAP ASAP ASAP ASAP ASAP ASAP

Answers:Combination reactions involve two elements that react together to form a chemical compound: A + B AB ie: N2 + 3 H2 2 NH3 Decomposition reactions involve a compound being broken down into its elements or simpler components: AB A + B ie: 2H2O 2H2 + O2 In a single replacement reaction, one element in a compound is substituted by another: AB + C CB + A ie: 2 Na(s) + 2 HCl(aq) 2 NaCl(aq) + H2(g) A double replacement reaction involves two compounds reacting with each other to form two different compounds:AB + CD AD + CB ie: NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s) Combustion: C10H8+ 12 O2 10 CO2 + 4 H2O Hope this helps :)

From Youtube

Decomposition Reaction Example :This is a short explaination, along with an example, of a decomposition reaction for my 9th grade chemistry project.

Chemistry - Synthesis, Decomposition and Combustion Reactions :GET the PowerPoint at www.ZUMAed.com. After a review of chemical reactions, this module presents a discussion of the characteristics of synthesis, decomposition, and combustion reactions, including examples of each. 3 By the end of this presentation, students will be able to * Describe what happens during a chemical reaction. * Identify signs that a chemical reaction has occurred. * Describe what happens during a synthesis, decomposition, and combustion reaction. * Identify and describe examples of synthesis, decomposition, and combustion reactions.