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# Examples of Decomposition Reaction

A chemical reaction involves the conversion of some chemical substances to new ones with the formation and cleavage of chemical bonds between atoms. There are various types of chemical reactions which depend upon the reactants, reaction conditions and other factors. Let’s have a look on certain type of chemical reaction which is known as decomposition reaction. In a decomposition reaction, one chemical substance decomposes into two or more chemical substances under suitable reaction conditions.

We can consider the decomposition reaction as the reverse process of synthesis or combination process. Remember a combination reaction involves the formation of a new chemical substance from the combination of two or more chemical substances. Let’s discuss some common examples of decomposition reaction.  Digestion of food in human body is an example of decomposition reaction. In digestion reaction, major constituents of our food like fats, proteins and carbohydrates decompose to form many simple substances.

The decomposition of thee Biomolecules releases a large amount of energy which provides energy to our body. The general chemical equation for the decomposition reaction can be written as given below;

AB A + B

There are several decomposition reactions in our surroundings. For example, electrolysis of water results the formation of oxygen and hydrogen gas. The chemical equation can be written as;

2 H2O → 2 H2 + O2

Similarly the decomposition of potassium chloride forms solid potassium and gaseous chlorine.

2 KCl(s) → 2 K(s) + Cl2(g)

On the basis of reaction conditions, the decomposition reactions can be classified in different types such as thermal decomposition, electrolytic decomposition and photo decomposition reaction. Thermal decomposition reaction or thermolysis involves the cleavage of one chemical substance into two or more simple substances in the presence of heat. These reactions are endothermic reactions as they require some heat to cleave the chemical bonds.
For example the calcium carbonate or lime stone forms calcium oxide and carbon dioxide in the presence of heat. This reaction is used in the manufacturing of cement.

CaCO3(s) + heat  CaO(s)  + CO2(g)

Similarly the decomposition of potassium chlorate also occurs in the presence of heat and form potassium chloride and oxygen. This is one of the preparation methods of oxygen in the laboratory.

2KClO3(s) + heat  2KCl(s)  + 3O2(g)

Sam reaction can be continued in the presence of manganese dioxide (MnO2) as catalyst.
The decomposition of ferric hydroxide and hydrated oxalic acid is also an example of thermal decomposition. The decomposition of ferric hydroxide forms ferric oxide and water whereas the decomposition of hydrate oxalic acid forms oxalic acid with water.

2Fe(OH)3 + heat → Fe2O3 + 3H2O
H2C2O4 .2H2 H2C2O4 + 2H2O

Another type of decomposition is electrolytic decomposition reaction which is also named as electrolysis. Such reactions occur in the presence of electricity in the aqueous solution.

For example electrolysis of water occurs in the presence of electricity to form hydrogen and oxygen gas whereas the electrolysis of sodium chloride forms molten sodium metal with chlorine gas.

2H2O(l) → 2H2(g)  + O2(g)
2NaCl (l) → 2Na (l) + Cl2(g)

Decomposition reactions can also occur in the presence of light and known as photo decomposition reaction or photolysis. For example silver chloride decomposes to form solid silver with chlorine gas.

2AgCl (s)  + Sunlight → 2Ag (s)  + Cl2 (g)

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 &rarr; A + B

with a specific example being the electrolysis of water to gaseous hydrogen and oxygen:

2H2O(I) &rarr; 2H2 + O2

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

2H2O2&rarr; 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&rarr; H2O + CO2

Other carbonates will decompose when heated producing the corresponding metaloxide and carbon dioxide. In the following equation M represents a metal:

MCO3&rarr; MO + CO2

A specific example of this involving calcium carbonate:

CaCO3&rarr; CaO + CO2

Metal chlorates also decompose when heated. A metal chloride and oxygen gas are the products.

2MClO3&rarr; 2MCl + 3O2

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

2KClO3&rarr; 2KCl + 3O2

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

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

Matrix decomposition

In the mathematical discipline of linear algebra, a matrix decomposition is a factorization of a matrix into some canonical form. There are many different matrix decompositions; each finds use among a particular class of problems.

## Example

In numerical analysis, different decompositions are used to implement efficient matrix algorithms.

For instance, when solving a system of linear equations Ax=b, the matrix A can be decomposed via the LU decomposition. The LU decomposition factorizes a matrix into a lower triangular matrixL and an upper triangular matrixU. The systems L(Ux)=b and Ux=L^{-1}b require fewer additions and multiplications to solve, though one might require significantly more digits in inexact arithmetic such as floating point. Similarly the QR decomposition expresses A as QR with Q a unitary matrix and R an upper triangular matrix. The system Q(Rx) = b is solved by Rx = QTb = c, and the system Rx = c is solved by "back substitution". The number of additions and multiplications required is about twice that of using the LU solver, but no more digits are required in inexact arithmetic because the QR decomposition is numerically stable.

## Decompositions related to solving systems of linear equations

### Rank factorization

• Applicable to: square, symmetric, positive definite matrix A
• Decomposition: A=U^TU, where U is upper triangular with positive diagonal entries
• Comment: the Cholesky decomposition is a special case of the symmetric LU decomposition, with L=U^T.
• Comment: the Cholesky decomposition is unique
• Comment: the Cholesky decomposition is also applicable for complex hermitian positive definite matrices
• Comment: An alternative is the LDL decomposition which can avoid extracting square roots.
• Applicable to: m-by-n matrix A
• Decomposition: A=QR where Q is an orthogonal matrix of size m-by-m, and R is an upper triangular matrix of size m-by-n
• Comment: The QR decomposition provides an alternative way of solving the system of equations Ax=b without inverting the matrix A. The fact that Q is orthogonal means that Q^TQ=I, so that Ax=b is equivalent to Rx=Q^Tb, which is easier to solve since R is triangular.

### Singular value decomposition

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:can you please give me examples of these chemical reactions 1. Synthesis 2. Decomposition 3. Single Displacement 4. Double Displacement

Answers:1. 2 H2(g) + O2(g)--->2 H2O,(l) synthesis 2 .2 H2O-(l)--> O2)g)+2 H2 (g) , decomposition 3. 2NaCl(aq)+ F2(g)--->2 NaF(aq)+ Cl2(g), single displacement 4. AgNO3(aq)+ NaCl(aq)---> AgCl(s) + NaNO3(aq), double displacement

Question:What are 5 real life examples of the 5 type of reactions? Combination/Synthesis Reaction Decomposition Reaction Single-Replacement Reaction Double-Replacement Reaction Combustion Reaction

Answers:Combination: the rusting of iron (4Fe + 3O2 2Fe2O3) Decomposition: the production of quicklime (Ca(OH)2 CaO + H2O) Single displacement: the polishing of silverware by soaking with aluminium (2Al + 3Ag2S 6Ag + Al2S3) Double displacement: the extraction of magnesium from seawater (MgCl2 + 2NaOH Mg(OH)2 + 2NaCl) Combustion: burning natural gas for heat (CH4 + 2O2 CO2 + 2H2O)