Transcript P R E P A R E D B Y SHAKTI PRASAD SATPATHY CLASS-X ,’B’ 1.CHEMICAL REACTION………………3  2.CHEMICAL EQUATION……………..4  3.WRITING A CHEMICAL EQUATION……….5  4.BALANCED CHEMICAL EQUATION………..6  5.BALANCING A CHEMICAL EQUATION…….7,8,9  5.TYPES OF.

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SHAKTI PRASAD SATPATHY
CLASS-X ,’B’
1.CHEMICAL REACTION………………3
 2.CHEMICAL EQUATION……………..4
 3.WRITING A CHEMICAL EQUATION……….5
 4.BALANCED CHEMICAL EQUATION………..6
 5.BALANCING A CHEMICAL EQUATION…….7,8,9
 5.TYPES OF CHEMICAL REACTION…………..10
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COMBINATION REACTION
DECOMPOSITION REACTION
DISPLACEMENT REACTION
DOUBLE DISPLACEMENT REACTION
OXIDATION AND REDUCTION
6.EFFECTS OF OXIDATION…………..15
CORROSION
RANCIDITY
CHEMICAL REACTION
 What
do you mean by chemical reaction?
 Chemical reaction is a process in
which new substances with new
properties are formed.
 Observations that helps us to determine
whether a chemical reaction has taken
place are:
 Change in state
 Change in colour
 Evolution of gas
 Change in temperature
CHEMICAL EQUATION
 What
is chemical equation ?
 The method of representing a chemical
reaction with the help of symbols and
formulae of the substances involved in it is
known as chemical equation.
 Reactants: The substances that undergo
different chemical change.
 Products: The new substances formed during
a chemical reaction.
WRITING A CHEMICAL EQUATION
 How

to write a chemical equation?
In a chemical equation, a chemical reaction
is written in terms of symbols of elements.
That means in place of names, symbols of
elements are used to indicate the reaction.
Thus, a chemical equation represents a
chemical reaction .

Ex: Mg(s) + o(g)

Cao(s)+H2O(1)
Mgo(s)
Ca(OH)2(aq)
BALANCED CHEMICAL EQUATION
What is balanced chemical equation?
 A chemical equation that has an equal
number of atoms of different elements in
the reactants and product.

 For
example:Zn+H2SO
In reactants
 No.of
Zn atoms
 No.of H atoms
 No.of S atoms
 No.of O atoms
1
2
1
4
ZnSO4 +H2
In products
1
2
1
4
The process of making the number of different types of atom
equal on both the sides of an equation is called balancing a
chemical equation.
 How to balance a chemical equation?
H2 + O2
H2O
 Step 1: first draw boxes around each formula. Do not change
anything inside the boxes.
 Step 2: List the number of atoms of different elements present
in the unbalanced equation.

Elements
No. of atoms in
reactants(LHS)
No. of atoms in
products(RHS)
Hydrogen(H)
2
2
Oxygen(O)
2
1
Step 3: we should first balance the compound
containing the maximum number of
atoms(reactants or product).in that
compound we have to select the element
which have the maximum number of atoms.
 To equalise the no. of atoms, it must be
remembered that we cannot alter the formulae
of the compounds or element involved in the
reactions.

Element
No. of atoms in
reaction(LHS)
No. of atoms in
products(RHS)
Hydrogen(H)
2
2
Oxygen(o)
2
1x2

H2 + O2
2H2O
This becomes partly balanced equation
 Step
4: in this equation , hydrogen molecule
is doubled in product. Let, us balance
hydrogen atoms in the partly balanced
equation. To equalise the no. of H atoms in
reactants we have to multiply 2 with the H
atoms in reactants.
Elements
Hydrogen(H)
Oxygen(O)
 Now
No. of atoms in
reactants.
No. of atoms in
products.
2x2 = 4
4
2
2
we have the balanced chemical
equation.
2H2 + O2
2H2O
TYPES OF CHEMICAL REACTION
 Some
important types of chemical
reactions are:-
Combination reactions
 Decomposition reactions
 Displacement reactions
 Double displacement reactions
 Oxidation and Reduction reactions

 Let
us start with the combination reactions.
 COMBINATION
REACTION: Reaction in which
a single product is formed from two or more
reactants is known as combination reaction.



For example: CaO(s) + H2O(1)
Ca(OH)2(aq)
The formation of water from hydrogen and oxygen is a
combination reaction.
2H2 (g) + O2 (g)
2HO2 (1)
 DECOMPOSITION
REACTION: Those reaction
in which a compound splits up into two or
more simpler substances are known as
decomposition reactions.

CaCO3 (s)
Heat
Cao(s) + CO2(g)
Decomposition

2FeSO4(S)
Heat
Fe2o3(s) + SO(g) +SO3(g)
 DISPLACEMENT
REACTION: Those reactions in
which one element takes the place of another
element in a compound are known as
displacement reactions.


ZnSO4 (aq)+ Cu(s)
Here zinc is the most reactive element which displaces the
copper.


CuSO4(aq) + Zn(s)
CuCl2 (aq)+Pb(s)
PbCl2 ( aq)+Cu(s)
Lead is more reactive element than copper.
 DOUBLE
DISPLACEMENT REACTION: Those
reactions in which two compounds react by an
exchange of ions to form new compounds are
called double displacement reaction.


AgNO3(aq) + NaCl(aq)
AgCl(s) + NaNO3(aq)
Here the silver ions reacts with chloride ions to form a
new compound, silver chloride.
OXIDATION
AND REDUCTION
 Oxidation:
(1) The addition of oxygen in a substance
during a reaction.
(2)Lose of hydrogen in a substance during a
reaction.


2Cu + O2 Heat 2CuO
H2S + Cl2
S + 2HCl
 Reduction:
(1) The addition of hydrogen in a substance
during a reaction.
(2)Removal of oxygen in a substance during a
reaction.


CuO + H2 Heat Cu + H2O
H2S + Cl2
S + 2HCl
addition of hydrogen
 Exothermic
reaction: The reactions in which
heat is released along with the product are
called as exothermic reaction.
For example:
 CH4(g) + 2O2 (g)
CO2 (g) +2H2O(g) + heat
o The reaction shows the burning of natural gas.
 Endothermic
reactions: The reactions in which
heat is absorbed along with the reactant to give
out the product is called endothermic reaction.

2Pb(NO3)2(s) Heat
2PbO(s) + 4NO2 (g) + O2 (g)
lead nitrate
lead oxide nitrogen dioxide oxygen
 Redox
reaction: The reactions in which one
reactant gets oxidised while the other gets
reduced is called redox reaction.

reduction
CuO + H2 Heat Cu + H2O
oxidation
Effects of oxidation in our daily life

THERE ARE TWO EFFECTS OF OXIDATION:
Corrosion
 Rancidity


CORROSION: When a metal is attacked by
substances around it such as moisture, acids,
etc., it is said to corrode and this process is
called corrosion.
o


The black coating on silver and the green coating on
copper are examples of corrosion.
Rusting of iron is the most common form of
corrosion.
When an iron object is left in damp air for a
considerable time it then coated with a reddish
brown powder.This process is commonly known
as rusting of iron.

Corrosion causes damage to car bodies,bridges,iron
railings,ships and to all objects made of metals especially
those of iron.
 Rancidity:
The condition produced by aerial
oxidation of fats and oils in foods marked by
unpleasant smell and taste is called rancidity.
 Prevention /retardation of development of
rancidity of food are:
 By adding anti-oxidants to foods contaning fats
and oils.
 There



are two types of anti-oxidants :
(1) BHA(Butylated Hydroxy-Anisole)
(2) BHT(Butylated Hydroxy-Toluene)
By storing food in air-tight container