Chapter 14 Chemical Effects of Electric Current Class 8 Notes

Conductors of Electricity

Metals such as copper, aluminium are good conductors of electricity while material like rubber plastics are bad conductors of electricity. In the case of liquids, some liquids are good conductors of electricity while a few are bad conductors of electricity. The water obtained from sources such as pumps, wells, ponds and tap are not pure and contain several dissolved salts. Such water is a good conductor of electricity. While distilled water is free of salt and is a bad conductor of electricity.

Chemical Effects of Electricity

The passage of electric current through a conducting solution results in chemical reactions. Following are the chemical reactions that can occur:

  • Gas bubbles formed on electrodes
  • Deposition of metals on electrodes
  • Colour change in the solution

The reactions depend on the solution and electrodes used.

Electroplating

The process of depositing a layer of the desired metal on another metal or material by means of electricity is known as electroplating. It is one of the applications of the chemical effects of electricity. It is mostly used in industries for coating over a metal a thin layer of desired metal. For example, chromium plating is done on objects such as car parts. Chromium has the following qualities that make it desirable:

  • Shiny appearance
  • Does not corrode
  • Resists scratches.

As chromium is expensive and is not economical to make the whole object out of chromium. A coating of chromium is done over a cheaper metal.

Class 8 Science Chapter 14 Questions

  1. Does pure water conduct electricity? If not, what can we do to make it conducting?
  2. Is it safe for the electrician to carry out electrical repairs outdoors during a heavy downpour? Explain.
  3. Prepare a list of objects around you that are electroplated.

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