The process of formation or breaking
of a chemical compound is called chemical reaction.
Digestive of food, process of respiration, Replication of DNA etc. are the example
of chemical reactioninside our body.
Elements or compounds combing in a chemical reaction are called reactants.
Similarly the elements or compounds formed as a result of chemical reaction
are called products.
Example of reactants and products
(C+O2 (Reactant) -------->CO2
(Product)
In 1785Lavoisier a French scientist proves
that by experimentally “Matter can neither be created nor destroyed during a
chemical reaction but it may undergo change in shape and composition”.
Addition Reaction: These reactions are also known as synthesis or
combination reactions. When two different element or compounds react together
to form a single compound then the reaction will be called an addition
reaction.
Example of addition reaction:
2H2 + O --------à 2H2O
Decomposition Reaction: Some compound on heating decomposes to
simpler compounds or elements. This type of reaction is called decomposition.
Example of
decomposition Reaction: CaCO3 -----à CO2 +
CaO
Heat evolved or absorbed during a chemical reaction is
called the heat of reaction.
There are two types of reactions with respect to energy
changes. (1) Exothermic
reaction(2) Endothermic reaction
Chemical reaction in which heat is released (cools) is called
exothermic reaction.
Chemical reaction in which heat is absorbed (hot) is called endothermic
reaction.
The total energy of the products in exothermic reaction
is less than that of the reactants.
In endothermic reaction total energy of the products
is more than that of reactants.
The life on this planet earth is possible due to the exothermic
reaction taking place in the sun.
2KClO3 ---------------------->
………. + 3O2 a) 3kcl
b) 2KCl
c) kcl
d) kcl
