What are the main types of chemical reactions?

A chemical reaction happens when one or more chemicals (Reactants) are changed into one or more other chemicals(Products). 

Examples: iron and oxygen combining to make rust.

Following are the types of chemical reactions: 

1. A combination reaction (also known as a synthesis reaction) is a reaction where two or more elements or compounds (reactants) combine to form a single compound (product). Such reactions are represented by an equation of the following form:

X $+$ Y → XY.

Example: H $+$ Cl --> HCl

2. A single-displacement reaction is a chemical reaction in which one element is replaced by another in a compound. It can be represented generically as:

 A $+$ B $-$ C → A $-$ C $+$ B

This will most often occur if A is more reactive than B, thus giving a more stable product.

Example: Reaction of iron nails with copper sulphate solution

Fe $+$ CuSO4 --> Cu $+$ FeSO4

3. A double-displacement reaction is a reaction in which the cations and anions of two ionic compounds exchange places to form two new compounds.

The general form of a double-replacement (also called double-displacement) reaction is: AB $+$ CD → AD $+$ BC.

Exmple: Pb(NO₃)₂ (aq) $+$ 2KI (aq) → 2 KNO₃ (aq) $+$ PbI₂ (s), in this case, a precipitate of lead (II) iodide is formed.

4. Decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds. These reactions often involve an energy source such as heat, light, or electricity that breaks apart the bonds of compounds.

Composition reaction is known as Decomposition reaction as a single compound breaks to give 2 or more new compounds.

AB --> A $+$ B

2 H2O (l) → 2 H2 (g) $+$ O2 (g)

5. A precipitation reaction is the formation of an insoluble salt when two solutions containing soluble salts are combined. The insoluble salt that falls out of solution is known as the precipitate. Precipitation reactions can help determine the presence of various ions in solution.

Examples of Precipitation Reaction: The reaction between silver nitrate (AgNO3) and sodium chloride (NaCl), results in the formation of silver chloride (AgCl) that is an insoluble salt.

6. A neutralization reaction is when an acid and a base react to form water and salt. It involves the combination of H+ ions and OH- ions to generate water. 

When a solution is neutralized, it means that salts are formed from equal weights of acid and base.

Acid $+$ Base --> Salt $+$ Water


Simply Easy Learning

Updated on: 10-Oct-2022


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