Question

Name the different types of chemical reaction. Give one example for each.

Answer 1

Hint: In a chemical reaction change in state, change in color, evolution of gas and change in temperature are some methods to determine whether a chemical reaction has taken place.

Complete Answer:
The substance that undergoes chemical change in the reaction is known as reactants and the new substance formed during the reaction is known as product. The total mass of the elements present in the products of a chemical reaction has to be equal to the total mass of elements present in reactants. A chemical reaction involves the breaking and making of bonds between atoms to produce new substances. Different types of chemical reactions are as follow:
Combination reactions are those reactions in which one or more than one compound or elements combine to form a new product or we can say in which a single product is formed from two or more reactants is known as combination reactions. Example of combination reactions are burning of coal \[\left( {{{\text{C}}_{\left( {\text{s}} \right)}} + {{\text{O}}_2}_{\left( {\text{g}} \right)} \to {\text{C}}{{\text{O}}_{2\left( {\text{g}} \right)}}} \right)\] and formation of water from hydrogen and oxygen \[\left( {2{{\text{H}}_{2\left( {\text{g}} \right)}} + {{\text{O}}_2}_{\left( {\text{g}} \right)} \to 2{{\text{H}}_2}{{\text{O}}_{\left( {\text{l}} \right)}}} \right)\] .
Decomposition reactions are those reactions in which one compound is broken down to form more substance or we can say a single reactant breaks down to give simpler products known as decomposition reactions. Example of decomposition reaction are decomposition of calcium carbonate to calcium oxide and carbon dioxide \[\left( {{\text{CaC}}{{\text{O}}_{3\left( {\text{s}} \right)}} \to {\text{Ca}}{{\text{O}}_{\left( {\text{s}} \right)}} + {\text{C}}{{\text{O}}_{2\left( {\text{g}} \right)}}} \right)\] and heating of lead nitrate which causes emission of nitrogen dioxide \[\left( {2{\text{Pb}}{{\left( {{\text{N}}{{\text{O}}_3}} \right)}_2} \to 2{\text{Pb}}{{\text{O}}_{\left( {\text{s}} \right)}} + 4{\text{N}}{{\text{O}}_{2\left( {\text{g}} \right)}} + {{\text{O}}_{2\left( {\text{g}} \right)}}} \right)\] .
Displacement reactions are those reactions which involve exchange of ions between compounds. Example of displacement reactions are displacement of copper by iron from copper sulphate solution \[\left( {{\text{F}}{{\text{e}}_{\left( {\text{s}} \right)}} + {\text{CuS}}{{\text{O}}_{4\left( {{\text{aq}}} \right)}} \to {\text{FeS}}{{\text{O}}_{4\left( {{\text{aq}}} \right)}} + {\text{C}}{{\text{u}}_{\left( {\text{s}} \right)}}} \right)\] and displacement of copper by lead from copper chloride solution \[\left( {{\text{P}}{{\text{b}}_{\left( {\text{s}} \right)}} + {\text{CuC}}{{\text{l}}_{2\left( {{\text{aq}}} \right)}} \to {\text{PbC}}{{\text{l}}_{2\left( {{\text{aq}}} \right)}} + {\text{C}}{{\text{u}}_{\left( {\text{s}} \right)}}} \right)\] .
Redox reactions are those in which one reactant is oxidized while the other gets reduced during reactions. Redox reactions are also known as oxidation reduction reactions. Example of redox reactions are oxidation of carbon to carbon monoxide and reduction of zinc oxide to zinc \[\left( {{\text{ZnO}} + {\text{C}} \to {\text{Zn}} + {\text{CO}}} \right)\] and redox reaction in which hydrochloric acid is oxidized to chlorine and manganese oxide gets reduced to manganese chloride \[\left( {{\text{Mn}}{{\text{O}}_2} + 4{\text{HCl}} \to {\text{MnC}}{{\text{l}}_2} + 2{{\text{H}}_2}{\text{O}} + {\text{C}}{{\text{l}}_2}} \right)\] .

Note: Reaction in which heat is evolved is known as exothermic reactions and on the other hand, reactions in which heat is absorbed are known as endothermic reactions. Burning of natural gas is an example of exothermic reaction and on the other hand decomposition reactions are mainly endothermic reactions.