Explain the following types of chemical reactions giving two examples for the each of them :
(a) combination reaction
(b) decomposition reaction
(c) displacement reaction
(d) double displacement reaction
Explain the following types of chemical reactions giving two examples for the each of them :
(a) combination reaction
(b) decomposition reaction
(c) displacement reaction
(d) double displacement reaction
(a) Combination reaction: A reaction in which two or more substances combine to form a single substance is called a combination reaction.
A + B → AB
e.g. (i) When iron and sulphur are heated together, they combine to form iron sulphide.
(ii) When carbon bums in oxygen to form a gaseous compound called carbon dioxide.
(b) Decomposition reaction: A reaction in which a compound breaks up due to the application of heat
into two or more simple substances is called a decomposition reaction.
e.g. (i) Mercuric oxide when heated, decomposes to form two elements mercury and oxygen
(ii) when heated CaCO3 decomposes to calcium oxide and carbon dioxide.
CaCO3Heat−−−→CaO+CO2
(c) Displacement reaction: A reaction in which a more active element displaces a less active element
from a compound is called a displacement reaction.
AB + C → CB + A
e.g. (i) Zinc, displaces copper from copper sulphate solution.
Zn+CuSO4(aq)→ZnSO4(aq)+Cu
(ii) Iron piece when added to copper sulphate solution, copper is displaced.
Fe+CuSO4→FeSO4+Cu .
(d) Double decomposition reaction: A chemical reaction in which two compounds in their aqueous state exchange their ions to form new compounds is called a double decomposition reaction.
AB + CD → CB + AD
e.g. (i) AgNO3+HCl→AgCl+HNO3 (aq)
(ii) NaOH(aq)+HCl(aq)→NaCl(aq)+H2O.
(a) Combination reaction: A reaction in which two or more substances combine to form a single substance is called a combination reaction.
A + B → AB
e.g. (i) When iron and sulphur are heated together, they combine to form iron sulphide.
(ii) When carbon bums in oxygen to form a gaseous compound called carbon dioxide.
(b) Decomposition reaction: A reaction in which a compound breaks up due to the application of heat
into two or more simple substances is called a decomposition reaction.
e.g. (i) Mercuric oxide when heated, decomposes to form two elements mercury and oxygen
(ii) when heated CaCO3 decomposes to calcium oxide and carbon dioxide.
CaCO3Heat−−−→CaO+CO2
(c) Displacement reaction: A reaction in which a more active element displaces a less active element
from a compound is called a displacement reaction.
AB + C → CB + A
e.g. (i) Zinc, displaces copper from copper sulphate solution.
Zn+CuSO4(aq)→ZnSO4(aq)+Cu
(ii) Iron piece when added to copper sulphate solution, copper is displaced.
Fe+CuSO4→FeSO4+Cu .
(d) Double decomposition reaction: A chemical reaction in which two compounds in their aqueous state exchange their ions to form new compounds is called a double decomposition reaction.
AB + CD → CB + AD
e.g. (i) AgNO3+HCl→AgCl+HNO3 (aq)
(ii) NaOH(aq)+HCl(aq)→NaCl(aq)+H2O.
