# What is chemical change ?
The change where compound having new properties can be formed is known as chemical change .
Example : NaCl + AgNO3 = AgCl + NaNO3
# What is chemical reaction ?
The process by which one or more substances is converted to one or more new substances is called a chemical reaction .
Example : NaOH + HCl = NaCl + H2O
# Different types of chemical reaction:
•Synthesis reaction
•Analysis reaction
•Decomposition reaction
•Combination or Addition reaction
•Substitution reaction
•Double decomposition reaction
•Isomeric reaction
•Hydrolysis reaction
•Neutralization reaction
•Polymerization reaction
•Oxidation – reduction reaction
1.Combination or Addition reaction:
The reaction in which a compound is formed by direct addition of two or more simple substances is called a combination or addition reaction.
Example : a) CaO + CO2 = CaCO3
2.Synthesis reaction
The reaction in which a compound is formed by direct addition of its constituent elements is called synthesis reaction.
Example: a) 2Na + Cl2 = 2NaCl
b) H2 + O2 = 2H2O
c) C + O2 = CO2
For your kind information all synthesis reactions are combination reaction but some combination reactions are not synthesis.
3.Analysis reaction
The reaction in which a compound is split up into two or more elements is called analysis reaction.
Example : a) 2Hg = 2Hg + O2
b) 2H2O = 2H2 + O2
c) 2HCl = H2 + Cl2
4.Decomposition reaction:
The reaction in which a compound is split up into two or more simpler substances is called decomposition reaction .
It is the opposite of addition reaction.
Example : a) CaCO3 = CaO + CO2
b) 2KClO3 = 2KCl + 3O2
c) NH4Cl = NH3 + HCl
5.Replacement or substitution reaction:
A reaction in which an element or a radical replaces another element or group from a compound and takes its place is called a substitution reaction .
Example : a) H2SO4 + Zn = ZnSO4 + H2
b) Zn + CuSO4 = ZnSO4 + Cu
6.Double decomposition reaction:
When two compounds react with each other and form two new compounds by the mutual exchange both of the radicals , it is called a double decomposition reaction .
Example : a) AgNO3 + NaCl = NaNO3 + AgCl
b)
7.Isomeric reaction :
A reaction in which the atoms in the molecule of a substance undergo rearrangement and produce a new substance is called a isomeric reaction .
Example : a) NH4CNO = H2N-CO-NH2
8.Hydrolysis reaction :
A reaction in which water reacts with any other compound forming two new substances is called hydrolysis reaction .
Example:
a) CH3COOC2H5 + H2O = CH3COOH + C2H5OH
b) Na2CO3 + 2H2O = 2NaOH + H2CO3
9.Oxidation – reduction (Redox) reaction :
A reaction in which one or more electrons are removed from atom or ion , on the other hand one or more electrons are accepted by atom or ion is called oxidation – reduction reaction .
Example: a) 2FeCl2 + Cl2 = 2FeCl3
10.Neutralization reaction:
A reaction in which an acid reacts with a base producing salt and water is called a neutralization reaction .
Example : a) NaOH + HCl = NaCl + H2O
11.Polymerization reaction:
Polymerization is a reaction in which two or more molecules of the same kind combined together and form a big molecule .
Example :
a) n CH2=CH2 = (-CH2-CH2-)n
