Chemical Effects Of Electric Current

Chemical Effects Of Electric Current

Electric Current

• We have learnt earlier that the materials,which allow electric current to pass through them,are good conductors of electricity.

• We found that metals such as copper and aluminium conduct electricity whereas materials such as rubber,plastic and wood do not conduct electricity.

Chemical Reactions

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. Deposits of metal may be seen on electrodes. Changes of colour of solutions may occur. The reaction would depend on what solution and electrodes are used. These are some of the chemical effects of the electric current.

Let us do a activity

• Join the free ends of the tester together for a moment. This completes the circuit of the tester and the bulb should glow. However, if the bulb does not glow, it means that the tester is not working. Can you think of the possible reasons? Is it possible that the connections are loose? Or, the bulb is fused? Or, your cells are used up? Check that all the connections are tight. If they are, then replace the bulb with another bulb. Now test if the tester is working or not. If it is still not working then replace the cells with fresh cells.

• (Caution: While checking your tester, do not join its free ends for more than a few seconds. Otherwise the cells of the battery will drain very quickly.)

William Nicholson

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. Oxygen bubbles formed on the electrode connected to the positive terminal of the battery and hydrogen bubbles formed on the other electrode

Electroplating

• You know that a brand new bicycle has shiny handlebar and wheel rims. However, if these are accidentally scratched, the shiny coating comes off revealing a not so shiny surface beneath. You might have also seen women using ornaments, which appear to be made of gold. However, with repeated use, the gold coating wears off, revealing silver or some other metal beneath.

• In both these cases, a metal has a coating of another metal. Do you wonder how a layer of one metal can be deposited on top of another? Well, let us try doing it ourselves.

• The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating. It is one of the most common applications of chemical effects of electric current.

What We Have learnt

• 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.