Course Content
CHAPTER 10: HALOALKANES AND HALOARENES
Topic Name 10 Haloalkanes and Haloarenes 10.1 Classification 10.2 Nomenclature 10.3 Nature of C–X Bond 10.4 Methods of Preparation of Haloalkanes 10.5 Preparation of Haloarenes 10.6 Physical Properties 10.7 Chemical Reactions
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CHAPTER 11: ALCOHOLS, PHENOLS AND ETHERS
Topic Name 11 Alcohols, Phenols and Ethers 11.1 Classification 11.2 Nomenclature 11.3 Structures of Functional Groups 11.4 Alcohols and Phenols 11.5 Some Commercially Important Alcohols 11.6 Ethers
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CHAPTER 13: AMINES
Topic Name 13 Amines 13.1 Structure of Amines 13.2 Classification 13.3 Nomenclature 13.4 Preparation of Amines 13.5 Physical Properties 13.6 Chemical Reactions 13.7 Method of Preparation of Diazonium Salts 13.8 Physical Properties 13.9 Chemical Reactions 13.10 Importance of Diazonium Salts in Synthesis of Aromatic Compounds
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CHAPTER 14: BIOMOLECULES
Topic Name 14 Biomolecules 14.1 Carbohydrates 14.2 Proteins 14.3 Enzymes 14.4 Vitamins 14.5 Nucleic Acids 14.6 Hormones
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CHAPTER 15: POLYMERS
Topic Name 15 Polymers 15.1 Classification of Polymers 15.2 Types of Polymerisation Reactions 15.3 Molecular Mass of Polymers 15.4 Biodegradable Polymers 15.5 Polymers of Commercial Importance
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CHAPTER 16: CHEMISTRY IN EVERYDAY LIFE
Topic Name 16 Chemistry in Everyday Life 16.1 Drugs and their Classification 16.2 Drug-Target Interaction 16.3 Therapeutic Action of Different Classes of Drugs 16.4 Chemicals in Food 16.5 Cleansing Agents
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Class 12th Chemistry Online Class For 100% Result
About Lesson

Battery:

Class 12 Electrochemistry Notes
Class 12 Electrochemistry Notes

Primary battery:

  • The reaction in a primary battery occurs only once.
  • The battery becomes dead after used onceand cannot be reused
  • Example of primary cell is dry cell and mercury cell.
  • The dry cell consists of a zincanode and the carbon (graphite) cathode surrounded by powdered manganesedioxide and carbon.

Secondary Battery

  • The reaction in a secondary battery occurs many times.
  • Once it exhausts it can be recharged and used again.
  • They are recharged by passing electric current through it in opposite direction.
  • Example of secondary cell is lead and nickel cadmium cell.
Class 12 Electrochemistry Notes

Fig. Nickel-Cadmium cell

  • It is used extensively in automobiles and invertors.
  • The lead cell contains a lead anode and a lead dioxide (PbO2) cathode and sulphuric acid is used as an electrolyte.
    Anode: Pb(s) + SO42–(aq) –> PbSO4(s) + 2e
    Cathode: PbO2(s) + SO42–(aq) + 4H+(aq) + 2e –> PbSO4 (s) + 2H2O (l)
  • The net cell reaction is:
    Pb(s)+PbO2(s)+2H2SO4(aq) –> 2PbSO4(s) + 2H2O(l)
  • While charging, the reaction within the battery is reversed and PbSO4(s) on anode and cathode is converted into Pb and PbO2, respectively.
  • It has a longer life thanlead storage cell and it requires more expenses to
  • The net reaction is:
    Cd (s)+2Ni(OH)3 (s) –> CdO (s) +2Ni(OH)2 (s) +H2O(l)

Fuel cells

Class 12 Electrochemistry Notes
Class 12 Electrochemistry Notes

Cathode: O2 (g) + 2H2O (l) + 4e –> 4OH(aq)
Anode: 2H2 (g) + 4OH(aq) ⎯ –> 4H2O(l) + 4e

  • The net reaction is:
    2H2(g) + O2(g) →2 H2O(l)

Corrosion

We all must have observed newly bought iron, silver or coper articles appears very shiny but with passage of time they get dull. This is due to the layer of metal oxide that develops on their surface. Rusting of iron, silver jewellery getting tarnished or copper articles getting covered by green layer. Metals react with atmospheric oxygen and produces metal oxides that are basic in nature because they react with water to form bases.

  • In case of rusting of iron, the iron reacts with the oxygen present in air and moisture and develops rust (hydrated iron (III) oxide).

Fig. Copper developing green coloured rust on exposure to moist air

  • In case of tarnishing of silver articles, the metallic silver reacts with hydrogen sulphide or sulphur present in air and gets tarnished.
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