CHAPTER- 11 CHEMICAL EFFECTS OF ELECTRIC CURRENT
NOTES
1. Conductors- Materials that allow the flow of electric current through them are called electrical conductors. Example- Iron, copper, etc.
2. Insulators- Materials that do not allow electric current to flow through them easily are called electrical insulators. Example- Wood, plastic, etc.
- Due to the heating effect of electric current, the filament of a bulb gets heated to a high temperature and glows. If the electric current in the circuit is weak, the filament does not get sufficiently heated and therefore does not glow.
- When we dissolve salt in distilled water, we get a salt solution. It is a good conductor of electricity.
- Water obtained from taps, hand pumps, wells, ponds, etc., is not pure. It contains various salts and is a good conductor of electricity. Distilled water, being free from salts, is a poor conductor.
- Chemical Effects of Electric Current- When electric current passes through a conducting solution, chemical reactions occur. As a result, gas bubbles may form on the electrodes, and the color of the solutions may change.
- In 1800, a British chemist, William Nicholson, demonstrated that if electrodes are immersed in water and electric current is passed through the solution, bubbles of oxygen and hydrogen are produced. Oxygen bubbles are formed on the electrode connected to the positive terminal of the battery, while hydrogen bubbles form on the other electrode.
- Electroplating- The process of depositing a layer of a desired metal on an object using electricity is called electroplating.
- Example- 1. Jewelers electroplate inexpensive metals with silver and gold to make jewelry.
3. For storing food items, tin containers are used, where tin is electroplated over iron.
- The disposal of used solutions from electroplating factories is also a major issue. It is a pollutant waste.
