topic of electrochemistry

3. The branch of chemistry that
deals with the relations between
electrical and chemical
phenomena is called
ELECTROCHEMISTRY.

4. WHO DISCOVERED
ELECTROCHEMISTR
Y?
•English
chemist John
Daniell (left) and
physicist Michael
Faraday (right), both
credited as founders
of electrochemistry
today.

5. WHAT ARE OXIDATION AND
REDUCTION?

7. Fe2O3+3CO----->2Fe+3CO2
•In this reaction 3CO gains oxygen
so it undergoes oxidation.

9. EXAMPLE OF OXIDATION:

10. •CH4+2O2---->CO2+2H2O+heat
•In this reaction O-atoms combine
with H-atom to form H2O,thus O-
atoms undergo reduction.

11. •An oxidation-
reduction (redox) reaction is a
type of chemical reaction that
involves a transfer of electrons
between two species.

18. •A photographic film is basically an emulsion of
silver bromide,(AgBr) in gelatin.
•Exposed film is placed in the developer
solution(Hydroquinone)that is actually a
reducing agent.

19. •Hydroquinone is an aromatic organic
compound that is a type of phenol, a
derivative of benzene, having the
chemical formula C₆H₄(OH)₂.

20. Hydroquinone Cream:

21. What is oxidation
state?

22. •Oxidation state or oxidation
number is defined as the number
of charges an atom will have in a
molecule or a compound.

23. •What are the rules for
assigning Oxidation
states?

24. 1.THE OXIDATION STATE OF ANY UNCOMBINED OR
FREE ELEMENTS IS ALWAYS ZERO.FOR
EXAMPLE:Zn,Na,H in H2.
2.IN SIMPLE IONS,OXIDATION STATE IS SAME AS
THEIR CHARGE.
3.IN COMPLEX IONS THE TOTAL SUM OF
OXIDATION STATES OF ATOMS IS EQUAL TO THE
CHARGE ON THEIR ION.
4.THE OXIDATION NUMBER OF EACH OF THE
ATOMS IN A MOLECULE OR COMPOUND IS
COUNTED SEPARATELY AND THEIR ALGEBRIC SUM
IS ZERO.

25. ELEMENTS OXIDATION STATES
Group-1 +1
Group-2 +2
Group-3 +3
H +1(except in metal hydrides where it is -1)
Group-7 -1
O -2(except peroxides and in OF2)

26. K2Cr2O7:
+2+2x+(-14)=0
2x-12=0
2x=12
x=+6

27. PERIODIC TABLE:

28. WHAT IS BREATH
ALYZER?

29. •Breath alyzer is a device used by
police to test a person’s breath for
alcohol.It is a strong oxidizing
agent.It contain an acidic solution
of potassium dichromate K2Cr2O7.

30. BREATH ALYZER:

32. Boric acid:

35. OXIDIZING AGENTS &
REDUCING AGENTS:

38. OXIDIZING AGENT:
• An oxidizing agent is the reactant
containing the element that is
reduced in the chemical reaction.

39. •A reducing agent is the
reactant containing the
element that is oxidized in the
chemical reaction.

40. 2Na+Cl2-------->2NaCl.
•Na is reducing agent as it is
oxidized whereas Cl2 is oxidizing
agent as it is reduced.

45. EXAMPLES OF
SPONTANEOUS PROCESS:

46. EXAMPLE OF NON-
SPONTANEOUS PROCESS:

47. ELECTROLYTE:

48. NON-ELECTROLYTE:

49. WHAT ARE
ELECTRODES:

55. At anode: X----->X+Ie-
At cathode: M+ + Ie- ------>M

56. GALVANIC
CELL(DANIEL
CELL):

58. ALLESSANDRO VOLTA &
JOHN FREDRICK DANIEL:

59. BATTERIES:

60. DRY CELL:

61. APPLICATIONS OF DRY
CELL:

62. Down’scell:

63. •Down cell is used for commercial preparation of sodium
metal(Na metal).
•It produces chlorine gas(Cl) as by product.
•On a large scale sodium metal is produced by the
electrolysis of fused NaCl.
•The electrodes are iron cathode and graphite anode.
•NaCl break into Na+ and Cl-
•Na ions move towards cathode and Cl ions move towards
anode.

64. AT ANODE: 2Cl------>Cl2(g)+2e-
AT CATHODE: 2Na+ +2e----->2Na

65. NELSON’S CELL:

66. •Nelson’s cell is used for commercial preparation of
sodium hydroxide(NaOH).
•It also produces chlorine and hydrogen gas as by
product.
•During electrolysis chloride ions move towards
anode(graphite).
•Sodium ions move towards cathode(perforated steel)

67. AT ANODE: 2Cl(aq)------->Cl2(g)+2e
At cathode: 2H2O(l)+2e-------->H2(g)+2OH(aq)
Overall reaction: 2Cl(aq)+2H2O(l)------>Cl2(g)+H2(g)+2OH(aq).

70. COPPER:

71. •Electroplating is the process of
plating one metal on to another by
hydrolysis.
There are also specific types
of electroplating such as copper
plating, silver plating, and
chromium plating.

74. ELECTROPLATING A SPOON
WITH SILVER:

75. ZINC PLATING:

77. TIN PLATING:

79. Corrosion of aluminium: