Chemical Reaction - Characteristic and Type (Full and clear explain)

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, viz, heat, light or electricity.

CHARACTERISTIC OF CHEMICAL REACTION :

1) Produce new substance

2) Irrevisible (permanent)

3) Don’t change the form of the objects

THE TYPE OF CHEMICAL REACTION :

Synthetis

Decomposition

Single displacement

Double displacement

Neutralization

Combustion

SYNTHETIS

Chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. A chemical synthesis begins by selection of compounds that are known as reagents or reactants. The word synthesis in the present day meaning was first used by the chemist Adolph Wilhelm Hermann Kolbe.

The other meaning of chemical synthesis is narrow and restricted to a specific kind of chemical reaction, a direct combination reaction, in which two or more reactants combine to form a single product. The general form of a direct combination reaction is:

A + B → AB

where A and B are elements or compounds, and AB is a compound consisting of A and B.

Examples of combination reactions include:

S + O2 → SO2 (formation of sulfur dioxide)

4 Fe + 3 O2 → 2 Fe2O3 (iron rusting)

4 special synthesis rules:

metal-oxide + H2O → metal(OH) - metal-chloride + O2 → metal-chlorate

non-metal-oxide + H2O → oxi-acid - metal-oxide + CO2 → metal(CO3)

COMBUSTION

Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.

In a complete combustion reaction, a compound reacts with an oxidizing element, such as oxygen or fluorine, and the products are compounds of each element in the fuel with the oxidizing element. For example:

CH4 + 2 O2 → CO2 + 2 H2O + energy

CH2S + 6 F2 → CF4 + 2 HF + SF6

A simple example can be seen in the combustion of hydrogen and oxygen, which is a commonly used reaction in rocket engines:

2 H2 + O2 → 2 H2O(g) + heat (the result is water vapor)

There are six types of combustion :

Complete vs incomplete

Incomplete

Smoldering

Rapid

Turbulent

Microgravity

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

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

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

SINGLE DISPLACEMENT

A single-displacement reaction, also called single-replacement reaction, is a type of oxidation-reduction chemical reaction when an element or ion moves out of one compound and into another. (One element is replaced by another in a compound.) This is usually written as

A + BX → AX + B

This will occur if A is more reactive than B. You can refer to the reactivity series to be sure of this.

A and B must be either:

- different metals (hydrogen's behavior as a cation renders it as a metal here), in which case X represents an anion, or

- halogens, in which case X represents a cation

In either case, when AX and BX are aqueous compounds (which is usually the case), X is a spectator ion.

All simple metal with acid reactions are single displacement reactions. For example the reaction between magnesium, Mg, and hydrochloric acid, HCl, forms magnesium chloride, MgCl2, and hydrogen, H2.

Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)

Cation replacement : AX + Y → YX + A

1. Cu + 2AgNO3 → 2Ag + Cu(NO3)2

2. Fe + Cu(NO3)2 → Fe(NO3)2 + Cu

Anion replacement : A + XY → XA + Y

1. Cl2 + 2NaBr → 2NaCl + Br2

2. Br2 + 2KI → 2KBr + I2

NEUTRALIZATION

In chemistry, neutralization is a chemical reaction whereby an acid and a base react to form a salt. Neutralization is also known as the specific type of double displacement reaction. Water is frequently, but not necessarily, produced as well. Neutralizations with Arrhenius acids and bases always produce water:

YOH + HX → XY + H2O

In non-aqueous reactions, water is not always formed. However, there is always a donation of protons (Brønsted-Lowry acid-base theory). Often, neutralization reactions are exothermic. For example, the reaction of sodium hydroxide and hydrochloric acid. An example of an endothermic neutralization is the reaction between sodium bicarbonate (baking soda) and acetic acid (vinegar).

DOUBLE DISPLACEMENT

Double displacement or metathesis is a molecular process involving the exchange of bonds between the two reacting chemical species, which results in the creation of products with similar or identical bonding affiliations. This is represented by the general reaction scheme:

AX + BY → BX + AY

3 types of double displacement reaction are :

1. Neutralization

2. Aqueous metathesis (precipitation)

3. Acid and carbonates

Example of aqueous metathesis : AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) ß precipitation of silver chloride from a mixture of silver nitrate and sodium chloride.

Example of acid and carbonates : HCH3COO (aq) + NaHCO3 (s) → NaCH3COO (aq) + CO2 (g) + H2O (l) ß a common science-fair "volcano" reaction involves the reaction of acetic acid with sodium bicarbonate.