science project chemistry- write all type of chemical reactions with examples.
Answers
The 5 primary types of chemical reactions are: Combination reaction. Decomposition reaction.
Combination Reaction. A reaction in which two or more reactants combine to form a single product is known as a combination reaction.
Decomposition Reaction.
Displacement Reaction.
Double Displacement Reaction.
Precipitation Reaction.
ANSWER :-
A chemical reaction is a change in which one or more substances or reactants react to form a new substance with different properties.
The reacting species (molecules, atoms, ions) are known as reactants and new species formed as a result of the reaction are called products.
EX:- N2 +3H2 = 2NH3
TYPES OF CHEMICAL REACTIONS :-
The chemical reactions are classified into different classes depending upon the type of chemical changes taking place.
1. COMBINATION REACTION :- A reaction in which two or more reactants combine to form a single product is called combination reaction.
EX :- 1. Calcium oxide (quick lime) reacts with water to form calcium hydroxide (slaked lime). The reaction is highly exothermic, as a lot of heat is produced during the reaction.
CaO + H2O --------- Ca(OH)2 + Heat
2. Burning of coal
C + O2 ----------- CO2
2. DECOMPOSITION REACTION :- a reaction in which a single reactant breaks down to form two or more products, is known as decomposition reaction.
This reaction is opposite to the combination reaction.
On the basis of the form of energy required for the reaction, these reactions are of three types:-
(i) THERMAL DECOMPOSITION :- These reactions use the energy in the form of heat for decomposition of the reactants.
EX :- (a) Calcium carbonate decomposes to give calcium oxide and carbon dioxide.
CaCO3 --------- CaO + CO2
(b) On heating lead nitrate, it decomposes to give yellow lead monoxide, nitrogen dioxide and oxygen gas.
2Pb(NO3)2 ---------------2PbO + 4NO2 + O2
(ii) ELECTROLYSIS DECOMPOSITION :- These reactions involves the use of electrical energy for the decomposition of the reactant molecule.
EX :- (a) When electric current is passed through water, it decomposes to give oxygen and hydrogen.
2H2O ----------- 2H2 + O2
(b) When electric current is passed through sodium chloride, it decomposes to give sodium metal and chlorine gas.
2NaCl ------------- 2Na + Cl2
(iii) PHOTOLYSIS DECOMPOSITION :- These reactions involves the use of light energy for the purpose of decomposition.
EX :- (a) When silver chloride is exposed to sunlight, it decomposes to give silver metal and chlorine gas.
2AgCl ------------ 2Ag + Cl2
3. DISPLACEMENT REACTION :- When a more reactive element displace less reactive element from its compound, it is called displacement reaction.
Displacement reaction can be classified into two types :-
(i) Single Displacement Reaction :- It is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound.
EX :- (a) Zinc being more reactive than copper, displace copper from copper sulphate solution and forms new product zinc sulphate and copper metal.
Zn + CuSO4 ------------ ZnSO4 + Cu
(b) Lead is more reactive than copper so it displace copper from its solution and white coloured lead chloride gets formed.
Pb + CuCl2 ----------- PbCl2 + Cu
(ii) DOUBLE DISPLACEMENT REACTION :- The reaction in which two different ions or groups of atoms in the reactant molecules are displaced by each other is called double displacement reaction.
EX :- (a) On adding sodium sulphate to barium chloride, a curdy white precipitate (PPT) of barium sulphate and a solution of sodium chloride are formed.
Na2SO4 + BaCl2 --------- BaSO4 + 2NaCl
(b) On adding silver nitrate solution to sodium bromide, a yellow precipitate of silver bromide and solution of sodium nitrate are formed.
AgNO3 + NaBr ---------- AgBr + NaNO3
(ii) Double Displacement Reaction :-