AP 8th Class Physical Science Notes Chapter 8 Chemical Effects of Electric Current
→ Electrode : An Electrode is a solid substance used as the point where current either enters or leaves the electrolyte or circuit.
→ Electroplating : The process of depositing a layer of any desired metal on another material, by means of electricity, is called electroplating.
→ Good conductor : The materials, which allow the electric current to pass through them, are good conductors of electricity.
→ Led : Light emitting Diode.
→ Poor Conductor : The materials, which do not allow the electric current to pass through them easily, are poor conductors of electricity.
→ The materials, which allow the electric current to pass through them, are good conductors of electricity.
→ The materials, which do not allow the electric current to pass through them easily, are poor conductors of electricity.
→ Examples of good conductors : Metals such as copper and aluminium are good conductors.
→ Examples of poor conductors of electricity : Rubber, plastic and wood.
→ Some liquids are good conductors of electricity and some are poor conductors.
→ The conductivity of liquids can be tested by using an LED electrical tester or a magnetic compass electrical tester.
→ Some liquids are good conductors of electricity and some are poor conductors.
→ Water is thus a good conductor of electricity. On the other hand, distilled water is free of salts and is a poor conductor.
→ 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.
→ If we pass current through a potato, a greenish blue spot forms around the wire connected to the positive terminal.
→ The passage of an electric current through a conducting solution causes chemical reactions.
→ 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 the chemical effects of currents.
→ The process of depositing a layer of any desired metal on another material, by means of electricity, is called electroplating.
→ When an electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. The free copper gets drawn to the electrode connected to the negative terminal of the battery and gets deposited on it.
→ Electroplating is a very useful process. It is widely used in industry for coating metal objects with a thin layer of a different metal.
→ Chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others.
→ Tin cans, used for storing food, are made by electroplating tin onto iron.
→ Tin is less reactive than iron. Thus, food does not come into contact with iron and is protected from getting spoilt.
→ A coating of zinc is deposited on iron to protect it from corrosion and formation of rust.