CBSE Class 8 Physics Notes for Chapter 4 Chemical Effects of Electric Current

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                 CHAPTER 4 CHEMICAL EFFECTS OF ELECTRIC CURRENT
 
Some liquids are good conductors of electricity and some are poor conductors of electricity.
A conducting solution is a liquid which allows electric current to pass through it. The passage of electric current through a conducting solution leads to chemical changes.
These chemical changes may be gas bubbles forming on the electrodes or metals deposit on the electrodes. The solution may change its colour.
 
ELECTROPLATING
Depositing a layer of one metal on another metals using electricity is called electroplating.
For example: To prevent iron from rusting, it is coated with a layer of copper. For this a solution of copper sulphate is made. The iron to be plated is made is negative terminal and a copper rod is made the positive terminal. When electric current is passed through the solution, the copper sulphate dissociates into copper and sulphate. The copper moves to the negative terminal i.e. the iron and gets deposited on the iron. The copper is restored in the solution from the positive electrode.
Uses of electroplating:

  • To plate gold and silver on less expensive metals.
  • To protect iron from corrosion.

 

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