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Types of Chemical Reactions

Reactions can be classified on the basis of their specific properties. Since there is no uniform criteria for classification, one reaction can fall into various types simultaneously.

Decomposition Reaction

A reaction is said to be decomposition reaction, if one reactant breaks up into two or more products in the process.

\ce{CaCO3 (s) -> CaO (s) + CO2 (g)}


Combination Reaction

A reaction is said to be combination reaction, if two or more than two reactants combine together to form a single product.

CaO(s) + H2O(l) ---->  Ca(OH)2 (aq) + Heat

Burning of coal

C(s) + O2(g)   ------>   CO2 (g)

Formation of water from H2 and O2

2H2 (g) + O2 (g) ------->  2H2O (l)

Burning of Natural gas

CH4 (g) + 2O2 (g) -------->  CO2 (g) + 2H2O


C6H12O6 (aq) + 6O2 (g) --------->  6CO2 (aq) + 6H2O (l) + energy



Exothermic Reaction

A reaction is said to be exothermic, if heat is generated during the reaction. Generally, most of the combination reactions are exothermic.

Endothermic Reaction

A reaction  is said to be endothermic, if heat is absorbed in the process. Generally, deocmposition reactions are endothermic.