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1. CLASS 10
Chemistry Chapter 1
Chemical Reactions and Equations
By Vinay Kumar Maurya
vinaykumarmaurya17852004@gmail.com

2. ● Physical change - Change in colour or state
occur but no new substance is formed. Example
- Water changes into steam on boiling but no
new substance is formed.
● Chemical change - One or new substance with
new physical and chemical properties are
formed. Example - when copper react with iron
two new substance that is ferrous sulphate and
copper are formed.
Fe(s) + CuSO4
(aq) → FeSO4
(aq) + Cu(s)
(BLUE) (GREEN)
Introduction to chemical reaction and equation

3. Observations that help to determine a
Chemical Reaction
a) Evolution of a gas
b) Change in temperature
c) Formation of a precipitate
d) Change in colour
e) Change of state

4. Representation of Chemical
Reaction
Representation of a chemical
reaction in terms of symbols
and chemical formulae of the
reactants and products is
known as a chemical equation.

5. Chemical Reactions and Equations-
• For solids, the symbol is “(s)”.
• For liquids, it is “(l)”.
• For gases, it is “(g)”.
• For aqueous solutions, it is “(aq)”.
• For gas produced in the reaction, it
is represented by “(↑)”.
• For precipitate formed in the
reaction, it is represented by “(↓)”.

6. Law of conservation of mass
The mass can neither be
created nor be destroyed
in an Chemical Reaction.

7. Balanced chemical equation
The chemical equation in
which the number of atoms
of each element in the
reactants side is equal to
that of the products side is
called a balanced chemical
equation.

8. How to balance Chemical Equation

9. How to balance Chemical Equation

10. Chemical Equation
A word equation is a chemical
reaction expressed in words rather
than chemical formulas. It helps
identify the reactants and
products in a chemical reaction.
For example,
Sodium + Chlorine → Sodium
chloride

11. Chemical Reaction
Chemical reactions are
chemical changes in
which reactants transfer
into product by making
or breaking of bonds or
both between different
atoms.

12. Types of Chemical Reactions
❖ Combination
❖ Decomposition
❖ Single displacement
❖ Double displacement
❖ Redox
❖ Endothermic
❖ Exothermic
❖ Precipitation
❖ Neutralization

13. Combination Reaction
In a combination reaction, two elements or
one element and one compound or two
compounds combine to give one single
product.
H2
+ Cl2
→ 2HCl
2CO + O2
→ 2CO2
NH3
+ HCl → NH4
Cl

15. Decomposition Reaction
A single reactant
decomposes on the
application of heat
or light or electricity
to give two or more
products.

16. Types of Decomposition Reaction
❏ Thermal Decomposition
Reaction
❏ Electronic Decomposition
Reaction or Electrolysis
❏ Photo Decomposition Reaction
or Photolysis

17. Thermal Decomposition Reaction
Decomposition reactions
which require heat –
thermolytic decompose
or thermolysis.

19. Electronic Decomposition Reaction
Decomposition reactions
which require electricity –
electrolytic decompose or
electrolysis.

21. Photo Decomposition Reaction
Decomposition reactions
which require light –
photolytic decomposition
or photolysis.

23. Single Displacement Reaction
More reactive element displaces
a less reactive element from its
compound or solution.

26. Double Displacement Reaction
An exchange of ions between
the reactants takes place to
give new products.

29. Precipitation Reaction
An insoluble compound called
precipitate forms when two
solutions containing soluble
salts are combined.

32. Exothermic reaction – heat is
evolved during a reaction. Most
of the combination reactions
are exothermic.
Al + Fe2
O3
→ Al2
O3
+ Fe + heat
CH4
+ 2O2
→ CO2
+ 2H2
O + heat
Exothermic Reaction

34. Endothermic Reaction
Endothermic – Heat is required to
carry out the reaction.
6CO2
+ 6H2
O + Sunlight → C6
H12
O6
+ 6O2
Most of the decomposition
reactions are endothermic

36. Neutralization Reaction
When acid reacts with
base it forms salt and
water 💦.

38. Redox Reaction
Oxidation and reduction take place
simultaneously.
Oxidation: Substance loses electrons
or gains oxygen or loses hydrogen.
Reduction: Substance gains
electrons or loses oxygen or gains
hydrogen.

39. Oxidising agent – a substance
that oxidises another
substance and self-gets
reduced.
Reducing agent – a substance
that reduces another
substance and self-gets
oxidised.

41. Corrosion
Gradual deterioration of a
material, usually a metal, by
the action of moisture, air
or chemicals in the
surrounding environment.

42. Rusting:
4Fe(s) + 3O2
(from air) +
xH2
O(moisture) → 2Fe2
O3
.xH2
O(rust)
Corrosion of copper:
Cu(s) + H2
O(Moisture) + CO2
(from
air) → CuCO3
.Cu(OH)2
(green)
Corrosion of silver:
Ag(s) + H2
S (from air) → Ag2
S(black) +
H2
(g)

44. Rancidity
It refers to the oxidation of fats
and oils in food that is kept for
a long time. It gives foul smell
and bad taste to food. Rancid
food causes stomach infection
on consumption.

45. Prevention
(i) Use of air-tight containers
(ii) Packaging with nitrogen
(iii) Refrigeration
(iv) Addition of antioxidants or
preservatives

46. Thankyou