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1. Prepared By:
AMIT KUMAR PANDEY
(SOFTCARE SOLUTION)
CHEMICAL
REACTIONS AND
EQUATIONS

2. CHEMICAL REACTIONS
AND EQUATIONS
• Module_01

4. Milk is left at room temperature
during summers
INTRODUCTIO
N

5. An iron tawa/pan/nail is left
exposed to humid atmosphere.

6. Grapes get fermented

7. Food is cooked

8. Food gets digested in
our body.

9. We respire

10. In all the above situations, the nature and the identity of the
initial substance have somewhat changed.
Whenever a chemical change occurs, we can say that a
chemical reaction has taken place.

11. Tongs
Magnesium
ribbon
Bunsen
burner
Magnesium
oxide
Activity
Hold it with a pair of tongs.
CAUTION: This Activity needs the teacher’s
assistance. It would be better if students wear
eye protection.
Clean a magnesium ribbon about 2 cm long by
rubbing it with sandpaper.
Burn it using a spirit lamp or burner and
collect the ash so formed in a watch-glass
as shown in
What do you observe?
Conclusion
 It is formed due to the reaction between
magnesium and oxygen.
 It changes into a white powder.
 As we have observed that magnesium
ribbon burns with a dazzling white
flame.
 This powder is magnesium oxide.

12. Test tube stand
Test tube
Activity
Potassium
iodide
Lead nitrate
solution
Lead iodide
 Yellow coloured precipitate of lead iodide
is formed.

13. st tube stand
Activity
Conical flask
Cork
Glass tube
Conclusion
 Formation of bubbles(Evolution of gas)
 Heat is given out (change of temperature)
 Change of state
dilute H2SO4
Zinc granules
Dilute sulphuric
acid
H2 gas

14. From the above three activities, we can say
that any of the following observations
helps us to determine whether a chemical
reaction has taken place –
Change in state
Change in colour
Evolution of a gas
Change in temperature
1
2
3
4
Formation of precipitate
5

15. CHEMICAL REACTIONS
AND EQUATIONS
• Module_02

16. CHEMICAL REACTIONS AND
EQUATIONS
Change in state

17. Change in colour

18. Evolution of a gas

19. Change in temperature

20. Formation of a precipitate

21. VALENCY
CHART
Cl–
Br–
OH
–
I–
NO3
–
Na
+
Ag+
AlO2
–
HCO3
–
H+
K+
sab ki
valency
hai 1
– Hydroxid
e
– Chlorid
e
– Bromid
e
– Iodid
e
– Nitrat
e
– Bicarbonat
e
– Aluminat
e
– Silver
– Sodium
– Hydroge
n
– Potassiu
m
Ca2+
Mg2+
Cd2
+
Hg2+
Zn2+
CO3
2–
CrO4
2–
O2–
Ba2+
SO4
2–
ZnO2
2–
sab ki
valency
hai 2
– Cadmiu
m
– Calciu
m
– Magnesiu
m
– Mercur
y
– Zinc
– Bariu
m
– Oxide
– Chroma
te
– Carbonat
e
– Sulphat
e
– Zincate
Copper - 1, 2
Copper (Cu) and Iron (Fe) both of them have variable valency
Iron - 2, 3
but
but Aluminium (Al) ki valency hai fixed
3
S2– – Sulphid
e
NH4
+ - Ammonium 1, Pb2+ - Lead

22. CHEMICAL
EQUATIONS
A simple representation of a
chemical reaction in words is called
a word equation.
Magnesiu
m
+ Oxyge
n
Magnesium oxide
Left Hand Side
(L.H.S)
Right Hand Side
(R.H.S)
Reactant
s
Product
s
Arrow indicates
• to yield
• shows the direction

23. A chemical equation is a short-hand
form for a chemical change.
Mg + O2 MgO
Left Hand Side
(L.H.S)
Right Hand Side
(R.H.S)
Reactant
s
Product
s
Arrow indicates
• to yield
• shows the direction
So above reaction is example of skeletal chemical equation.
If the number of atoms of each element on the both sides is same then it is balanced
equation else equation is unbalanced or skeletal chemical equation.

24. STEPS INVOLVED IN WRITING CHEMICAL
EQUATION
Mg(s) + O2(g) MgO(s)
∆
1) Reactants: _______ and Products: _______
2) Reactants and Products: separated by an __________
3) 2 or more reactants /products: separated by
______________
4) Conditions: mentioned _____________
5) ____________________ of reactants and product:
to make reaction more informative
Reactant
s
Product
s
LHS RHS
ARROW
PLUS(+)SIGN
ON ARROW
PHYSICAL STATES
(s) (g
)
(s)

25. CHEMICAL REACTIONS
AND EQUATIONS
• Module_03

27. LAW OF CONSERVATION OF MASS :
Mass can neither be created nor
destroyed in a chemical reaction. That is,
the total mass of the elements present in
the products of a chemical reaction has
to be equal to the total mass of the
elements present in the reactants.
A + B AB
Total mass of
elements in the
reactants
Total mass of
elements in the
products
=

28. Elemen
t
Reactants
(LHS)
Products
(RHS)
Number of
atoms
Number of
atoms
Zn
H
S
O
1 1
2 2
1 1
4 4
Zn H2
+
ZnSO4
H2SO4
+
Zinc + Sulphuric
acid
Zinc
sulphate
+ Hydrogen
 As per law of
conservation of mass :
 As the number of
atoms of element is
the same on the both
sides of the arrow.
Hence it is a balanced
chemical equation.

29. Element
Reactants
(LHS)
Products
(RHS)
Number of
atoms
Number of atoms
Fe
H
O
1 3
2 2
1 4
Fe +
H2O
Fe3O4
 Draw boxes around each
formula
Step I
Step II
 List the number of atoms
of different elements
+
H2

30. Atoms of
oxygen
In reactants In products
(i) initial
(ii) To balance
1in H2O 4 in (Fe3O4)
1 x
4
4
 Start balancing the
compound that contains
maximum no of atoms
 To balance the oxygen
atoms.
Step III
 We can not alter the
formulae of the compounds
or elements to equalise the
number of atoms.
 For example to balance
oxygen atoms we can put
coefficient 4 as 4 H2O and
not H2O4 or (H2O)4
4
Fe3O4
Fe +
H2O
Fe3O4 +
H2

31. Atoms of
hydrogen
In reactantsIn products
(i) initial
(ii) To balance
8 (in 4
H2O)
2 ( in H2)
8 2x
4
 Let us balance hydrogen
atoms in the partly
balanced equation.
Step IV
4
4
Fe +
H2O
Fe3O4 +
H2

32. Atoms of Iron In reactants In products
(i) initial
(ii) To balance
1 (in Fe) 3 ( in Fe3O4)
1 x
3
3
 Let us balance Iron
atoms in the partly
balanced equation.
Step V
3 4
4
Fe +
H2O
Fe3O4 +
H2

33.  Check the correctness of
the balanced equation.
Step VI
 This method of balancing
chemical equations is
called hit -and-trial
method.
3 4
4
Fe +
H2O
Fe3O4 +
H2

34.  The physical states of the
reactants and products
are mentioned along with
their chemical formulae.
Step VII
 The gaseous, liquid,
aqueous and solid states
of reactants and products
are represented by the
notations (g), (l), (aq) and
(s).
So the balance equation becomes
3 Fe (s) + 4 H2O (g) Fe3O4 (s) + 4 H2 (g)

35.  Sometimes the reaction
conditions, such as
temperature, pressure,
catalyst, etc., for the
reaction are indicated
above and/or below the
arrow in the equation.
Step VIII
CO (g) + 2 H2 (g) CH3OH (I)
For example
340
atm
6 CO2
(aq)
+ 12 H2O (I) C6H12O6 (aq)
Sunlig
ht
Chlorophy
ll
+ 6 O2 (aq) + 6 H2O (I)

36. CHEMICAL REACTIONS
AND EQUATIONS
• Module_04

37. TYPES OF CHEMICAL
REACTIONS
We have learnt that during a chemical reaction atoms of one element do not
change into those of another element.
Nor do atoms disappear from the mixture or appear from elsewhere.
Actually, chemical reactions involve the breaking and making of bonds
between atoms to produce new substances.

38. C
CO2 O
O
BURNING OF
COAL
C(s
)
+ O2(g) CO2(g
)
Carbo
n
Oxygen Carbon
dioxide

39. FORMATION OF
WATER
 One atom of oxygen
combines with two
atoms of hydrogen to
form water molecule.
O
H2O H
H
2
H2(g)
+ O2(g
)
2H2O(
l)
Hydroge
n
Oxygen Water

40. AB
B
A
COMBINATION
REACTION
+
A chemical reaction in which two or more reactants combine to form a
Single product, is called COMBINATION REACTION.

41. 30
o
Water
Calcium oxide
Slaked
lime
25°
CaO(s) H2O(l)
+ Ca(OH)2(aq)
Quick lime Slaked lime
Water

42. Ca (OH)2(aq) + CO2(g
)
CaCO3(s) + H2O(I)
Calcium hydroxide Calcium carbonate
 A solution of slaked lime produced is used for
white washing walls.
 Calcium hydroxide reacts slowly with the
carbon dioxide in air to form a thin layer of
calcium carbonate on the walls.
 Calcium carbonate is formed after two to three
days of white washing and gives a shiny finish
to the walls.
 It is interesting to note that the chemical
formula for marble is also CaCO3.
Carbon
dioxide
Wate
r

43. CHEMICAL REACTIONS
AND EQUATIONS
• Module_05

44. I. Burning of natural gas :
CH4(s
)
+ O2(g) H2O (g) Heat
Methane Oxygen Wate
r
EXOTHERMIC
REACTION
2 CO2(g
)
+ +
Carbon
dioxide
Reactions in which heat is
released along with the
formation of products are called
exothermic chemical reactions.
2

45. i. Respiration reaction :
C6H12O6(aq
)
+ O2(aq
)
H2O (l) Energ
y
Sugar Oxygen Wate
r
6 CO2(aq
)
+ +
Carbon
dioxide
6 6

46. The decomposition of vegetable matter into compost is also an example of an
exothermic reaction.

47. Endothermic reaction
Wire gauze
Burne
r
Iron
Sulphur
Iron sulphide
Fe(s
)
+
S(s)
FeS(s)
+ Hea
t
Iro
n
Sulphu
r
Iron
sulphid
e
 Reactions in which heat is absorbed are
called endothermic chemical reactions.
Tripod
stand

48. CHEMICAL REACTIONS
AND EQUATIONS
• Module_06

49. A
DECOMPOSITION
REACTION
+
A chemical reaction in which a compound is split into two or more
simple substances is called as DECOMPOSITION REACTION.
AB B

50. DECOMPOSITION
REACTION
Electrolysis of water
HEA
T
ELECTRICI
TY
LIGHT
ENERGY
Can take place under 3 conditions

51. Bunsen
burner
Carbon
dioxide gas
Calcium
carbonate
CaCO3(s
)
Heat CaO(s)
Calcium
carbonate
Calcium
oxide
CO2(
g)
+
Carbon
dioxide
Turns
milky
Used in Manufacturing
of cement
Calcium hydroxide
solution (lime
water)
Calcium
oxide
(Limestone) (Quick
lime)
HEATING OF CALCIUM
CARBONATE

52. HEATING OF FERROUS
SULPHATE
Bunsen burner
Ferrous sulphate crystals
Do not point the mouth of boiling
tube at your neighbours or
yourself.
FeSO4(s
)
Hea
t
Ferrous
sulphate
Ferric
oxide
SO2(g
)
+
Ferrous oxide
Fe2O3(S) SO3(g
)
+
Sulphur
dioxide
Sulphur
trioxide
2
FeSO4.7H2
O
Hea
t
Green
7H2O
+
FeSO4
Water
Colourless
Smell ?

53. HEATING OF LEAD NITRATE
Bunsen burner
Lead nitrate
Lead oxide
Pb(NO3)2(
s)
PbO(s)
Lead
nitrate
Lead
oxide
NO2(s
)
+
Heat
Nitrogen
dioxide
O2(g)
+
2 2 4
Oxyge
n
Brown fumes
of nitrogen oxide
A decomposition reaction carried out by heating is
called as, Thermal decomposition reaction.

54. THERMAL DECOMPOSITION REACTION
Test
tube
Bunsen
burner
Sugar
C12H22O11(s
)
C(s
)
Suga
r
Carbo
n
+
∆ H2O(g)
12
Water
11
indicates evolution
of gas

55. A decomposition reaction carried out by heating is
called as, Thermal decomposition reaction.
HEATING OF CALCIUM
CARBONATE
HEATING OF FERROUS
SULPHATE
HEATING OF LEAD
NITRATE
HEATING OF SUGAR
So we conclude

56. CHEMICAL REACTIONS
AND EQUATIONS
• Module_07

57. AgBr(
s)
Ag(s)
Silver
bromide
Silve
r
+
Sunligh
t
Br2(g)
2 2
Bromin
e
AgCl(s) Ag(s)
Silver
chloride
Silver
+
Sunlig
ht
Cl2(g)
2 2
Chloride
Decomposition due to light is called
Photolysis.
DECOMPOSITION REACTIONS DUE TO
LIGHT
Silver
bromide

58. Both these reactions are used in
black and white photography
during the process of developing.

59. Cathode
Switch
Rubber
stopper
Acidified water is used to produce
ions (ionisation)
Uses of electrolysis:
Extraction of metals like sodium,
aluminium electroplating
Water
Plastic mug
Test tube
Graphite rod
Anode
Dilute
sulphuric acid
Acidified water is the water mixed
with few drops of acid
Decomposition due to Electricity
is called Electrolysis.
H2O(l) H2(g) O2(g
)
+
Electricit
y
2
2
Water Hydroge
n
Oxygen
Hydrogen
Oxyge
n

60. CHEMICAL REACTIONS
AND EQUATIONS
• Module_08

61. K
Na
Ca
Mg
Al
Zn
Fe
Pb
Cu
Hg
Ag
Au
Potassiu
m
Sodiu
m
Calciu
m
Magnesiu
m
Aluminium
Zin
c
Iro
n
Lead
Coppe
r
Mercury
Silver
Gold
[H] Hydrogen
REACTIVITY SERIES OF METALS
Most
reactive
The arrangement of metals in
the increasing or decreasing
order of reactivity is called the
reactivity series of metals.
Least
reactive
Reactivity
decreases

62. CB
A
DISPLACEMENT
REACTION
+
When a more reactive element removes another (similar) element,
having less reactivity, from its compound, these reactions are termed
as DISPLACEMENT REACTIONS.
AB C
+

63. Sand
paper
Iron nail
Copper sulphate
solution
20 Mins
Ferrous sulphate
solution
CuSO4(aq)
Copper sulphate
+ Fe(s
)
Iron
FeSO4(aq
)
Iron
sulphate
+ Cu(s)
Copp
er K
Na
Ca
Mg
Al
Zn
Fe
Pb
Cu
Hg
Ag
Au
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Lead
Copper
Mercury
Silver
Gold
Li Lithium
Sn Tin

64. Zn(s)
Zinc
+ CuSO4(aq
)Copper
sulphat
e
ZnSO4(aq
) Zinc
sulphate
+
Copp
er
Cu(s)
Pb(s
)
Lea
d
CuCl2(a
q)
Copper
chlorid
e
PbCl2(a
q)Lead
chloride
Copp
er
Cu(s)
+
+ Zinc displaces
copper
Lead displaces
copper
K
Na
Ca
Mg
Al
Zn
Fe
Hg
Ag
Au
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Mercury
Silver
Gold
Li Lithium
Sn Tin
Pb
Cu
Lead
Copper

65. CHEMICAL REACTIONS
AND EQUATIONS
• Module_09

66. DOUBLE DISPLACEMENT
REACTION
C+B-
A+D-
+
A+B-
C+D-
+
The reactions where a precipitate is formed by exchange of ions
between the reactants, are examples of double displacement reactions.
During double displacement reaction an insoluble substance is form
known as precipitate.
Any reaction that produces a precipitate can be called a precipitation
reaction.

67. Test tube containing solution of
sodium sulphate
Test tube
containing
solution of
barium chloride
REACTION BETWEEN BARIUM CHLORIDE AND SODIUM SULPHATE
Na2SO4(aq)
Sodium
sulphate
+ BaCl2(aq
)
Barium
chlorid
e
BaSO4(s)
Barium
sulphate
+ NaCl(aq)
Sodium
chlorid
e
(white ppt)
2
+ - + - + - + -

68. BaS + ZnSO4 ZnS
Barium
sulphide
Zinc
sulphate
Zinc sulphide
BaSO
4
+
Barium
sulphate
Precipitate is symbolized by an
arrow pointing downwards
+ - + - + - + -
(white ppt)
CuCl2 (aq) + KI (aq) KCl(aq)
Copper
chloride
Potassium
iodide
Potassium
chloride
CuI2(s) +
Cupric
iodide
+ - + - + - + -
(brown
ppt)
2 2

69. CHEMICAL REACTIONS
AND EQUATIONS
• Module_10

70. OXIDATION AND REDUCTION
REACTION

71. Wire gauze
Tripod stand
Bunsen burner
Copper powder
Copper (II) oxide
China dish
OXIDATION
REACTION
Cu(s) + O2(g
)
Coppe
r
Oxyge
n
CuO(s)
Copper
oxide
2 2
Copper is gaining oxygen to form copper oxide.

72. C2H5OH(
l)
+ Na
Ethyl
alcohol
Sodiu
m
C2H5ONa
Sodium ethoxide
Ethyl alcohol has lost hydrogen
2
2 2 + H2
Hydrogen
gas
Hence, oxidation is the gain of
oxygen or loss of hydrogen.
H H

73. C + H
2
Carbo
n
Hydroge
n
CH4
Methan
e
REDUCTION REACTION
O3 O2
Ozon
e
Oxygen
[O]
Nascent
oxygen
Hydrogen
gain
Oxygen lost
+
Reduction is the loss of oxygen or
gain of hydrogen.
2

74. CHEMICAL REACTIONS
AND EQUATIONS
• Module_11

75. REDOX
REACTION

76. REDOX REACTION
When oxidation and reduction take place simultaneously in a given
chemical reaction, it is known as REDOX REACTION.

77. Cu
O
+ H2 Cu + H2O
(O2
lost)
(O2
added)
Oxygen is being removed
from CuO
CuO is changing to Cu
Copper oxide is being
reduced to copper
Oxygen is being added to
hydrogen
H2 is changing to H2O
Hydrogen is being
oxidised to water
Reductio
n
Oxidatio
n
CuO gives oxygen for
Oxidation
OXIDISING
AGENT
(The substance which gives
oxygen for oxidation is
called an oxidising agent)
H2 REMOVES
oxygen
REDUCING
AGENT
(The substance which
removes oxygen is called as
reducing agent)

78. BaSO4 + C BaS + C
O
4
4
(O2 lost)
(O2
added)
Reducti
on
Oxidatio
n
OXIDISING
AGENT
REDUCING
AGENT
BaSO4 C

79. ZnO + C Zn + C
O
(O2 lost)
(O2
added)
Reducti
on
Oxidatio
n
OXIDISING
AGENT
REDUCING
AGENT
ZnO C

80. MnO2 + HCl MnCl
2
+ H2O
4 2 + Cl2
(O2 lost)
(O2
added)
Reducti
on
Oxidatio
n
OXIDISING
AGENT
REDUCING
AGENT
MnO2 HCl

81. CHEMICAL REACTIONS
AND EQUATIONS
• Module_12

82. The slow process of decay
or destruction of metal due
to the effect of air,
moisture, acids on it is
known as CORROSION.
CORROSIO
N
Due to effect of moisture a
layer of reddish brown colour
is deposited over surface of
iron, called rust. Its chemical
formula is Fe2O3.H2O.

83. Copper objects get coated with
a green substance called
copper carbonate with the
passage of time.
This green substance is formed
the due to the reaction of
copper with carbon dioxide and
moisture present in the
atmosphere.
Copper

84. Silver objects become
blackened and lose their
shining with the passage of
time.
This happens due to the
reaction of silver with hydrogen
sulphide gas present in the
atmosphere.
Silver

85. RANCIDIT
Y
When oil and fats
are oxidized or even
allowed to stand for
a long time, they
become RANCID.
Food smells foul and its taste changes.

86. TO PREVENT
RANCIDITY
Food is placed in air
tight container
Chips are stored in
nitrogen as nitrogen is
least reactive
 Antioxidants are used to prevention oxidation of food containing fats
and oils.
 Food are also stored in refrigerator as low temperature reduces the rate
of reaction
 It is also advised to store food away from sunlight, as sunlight can
increase the rate of reaction

87. Thank You
SOFTCARE SOLUTION
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