CHEMICAL EFFECTS OF ELECTRIC CURRENT

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. 

1. Some liquids are good conductors of electricity and some are poor conductors. 
2. Most liquids that conduct electricity are solutions of acids, bases and salts. 
3. The passage of an electric current through a conducting liquid causes chemical reactions. 
4. The resulting effects are called chemical effects of currents. 

WATER: IS IT A CONDUCTOR OR AN INSULATOR?

1. The water that we get from sources such as tap, hand pumps, wells, ponds is not pure but a solution.
2. The small number of mineral salts are naturally present in it.
3. This water is thus a conductor of electricity.
4. On the other hand, distilled water is free of salts, and thus an insulator.
On passage of electric current through a solution following chemical effects may be seen: 
(i) Bubbles of a gas on electrodes
(ii) Deposits of metal on electrodes
(iii) Change of colour of solution

CONDITION OF ELECTRICITY BY LIQUIDS:

(i) Liquids containing salts, acids or bases conduct electricity. 
(ii) Distilled water does not conduct electricity because it does not have free ions. 
(iii) The liquid which conducts electricity and undergoes decomposition is called the electrolyte. 
(iv) The electrode connected to the positive terminal of battery is called anode while the connected to the negative terminal is called cathode. 

ELECTROLYSIS

The chemical decomposition of constituents solution on passage of electric current.

ELECTROPLATING

1. It is the process of depositing a thin layer of a metal on any conducting substance by the process of electrolysis. 
2. The object to be electroplated is made the cathode (negative electrode) by connecting it to the negative terminal of the battery.
3. The metal which has to be deposited is made the anode (positive electrode) by connecting it to the positive terminal of the battery.
4. The electrolyte is usually a salt solution of the metal to be coated.

SOME ELECTROPLATED OBJECTS

APPLICATIONS OF ELECTROPLATING:

(i) Metals that rust are often coated with other metals to prevent rusting. 
(ii) Chromium plating is found on bath taps, car bumpers, etc. to give a bright attractive appearance and resist scratches and wear. 
(iii) Silver plating is done on cutlery and jewellery items. 
(iv)Tin cans, used for storing food, are made by electroplating tin onto the iron. 
Tin is less reactive than iron as a result food does not come into contact with iron and is protected from getting spoilt. 
(v)Iron is used in bridges and automobiles to provide strength. 
A coating of zinc is deposited on iron to protect it from corrosion the and formation of rust. 

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