CBSE – 8th Standard Science

Chemical Effects Of Electric Current

  • The materials, which allow electric current to pass through them, are good conductors of electricity.
  • Materials, which do not allow electric current to pass through them easily, are poor conductors of electricity.
  • Metals such as copper and aluminum conduct electricity whereas materials such as rubber, plastic and wood do not conduct electricity.
  • Electric current produces magnetic effect.
  •  Most liquids that conduct electricity are solutions of acids, bases and salts.
  •  Some liquids are good conductors of electricity and some are poor conductors.image001
  • When salt is dissolved in distilled water, we obtain salt solution. This is a conductor of electricity.
  • In 1800, a British chemist, William Nicholson (1753–1815), had shown that if electrodes were immersed in water, and a current was passed, bubbles of oxygen and hydrogen were produced.
  • The passage of an electric current through a conducting solution causes chemical reactions.

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  • The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.

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  • Electroplating is the most common applications of chemical effects of electric current process. It is widely used in industry for coating metal objects with a thin layer of different metals.
  • Jewellery makers electroplate silver and gold on less expensive metals.
  • Tin cans, used for storing food, are made by electroplating tin onto iron.
  • A coating of zinc is deposited on iron to protect it from corrosion and formation of rust.
  • In the electroplating factories the disposal of the used conducting solution is a major concern. It is a polluting waste and there are specific disposal guidelines to protect the environment.
  • The passage of an electric current through a conducting solution causes chemical reactions. As a result, bubbles of a gas may be formed on the electrodes.
  • Some liquids are good conductors of electricity and some are poor conductors.
  • The passage of an electric current through a conducting liquid causes chemical reactions.
  • The resulting effects are called chemical effects of currents.

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  • We found that metals such as copper and aluminum conduct electricity whereas materials such as rubber, plastic and wood do not conduct electricity.
  • However, so far we have used our tester to test materials which were in solid state. But what about liquids
  • When the free ends of the tester do not touch each other, there is an air gap between them.
  • Air is a poor conductor of electricity. But during lightning, an electric current passes through air.
  • Whether other materials classified as poor conductors also allow electricity to pass under certain conditions.
  • Some liquids are good conductors of electricity and some are poor conductors.
  •  Most liquids that conduct electricity are solutions of acids, bases and salts.
  •  The passage of an electric current through a conducting liquid causes chemical reactions.
  • The resulting effects are called chemical effects of currents.
  •  The process of depositing a layer of any desired metal on another material, by means of electricity, is called electroplating.

CBSE 8th Standard Science

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CBSE 8th Standard Science Syllabus and Revision Notes

  • Crop Production & Management
  • Microorganisms – Friends & Foe
  • Synthetic, Fibers & Plastic
  • Materials – Metals & Non-Metals
  • Coal & Petroleum
  • Combustion & Flame
  • Conservation Of Plants And Animals
  • Cell Structure And Functions
  • Reproduction In Animals
  • Reaching The Age Of Adolescence
  • Force And Pressure
  • Friction
  • Sound
  • Chemical Effects Of Electric Current
  • Some Natural Phenomena
  • Light
  • Stars And The Solar System
  • Pollution Of Air And Water