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Electric Current: Ions Powering Electric Flow
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Conduction of electricity in liquids, also known as electrolytic conduction, involves the movement of charged particles within the liquid. In this process, ions, which are electrically charged atoms or molecules, facilitate the flow of electric current.
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Conduction of Electricity: Conductors and Insulators Explained
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- Liquids as Conductor: Some liquids are good conductors of electricity and some are poor conductors.
- Under certain conditions most materials can conduct electricity.
- Example: Dipping the ends of the tester into lemon juice or vinegar shows, when the liquid between the two ends of the tester allows the electric current to pass, the circuit of the tester becomes complete.
- The current flows in the circuit and the bulb glows.
- Incomplete Circuit: When the liquid does not allow the electric current to pass, the circuit of the tester is not complete and the bulb does not glow.
- Exceptional Situations: In some situations even though the liquid is conducting, the bulb may not glow.
- Weak Current: As a result, the circuit of the tester may be complete and yet the current through it may be too weak to make the bulb glow.
- Salt Water as Good Conductor: The water from sources such as taps, hand pumps, wells and ponds is not pure. It may contain several salts dissolved in it.
- This water is thus a good conductor of electricity.
- Distilled Water as Poor Conductor: Distilled water is free of salts and is a poor conductor, but when salt is dissolved in distilled water, it becomes a conductor of electricity.
- Most liquids that conduct electricity are solutions of acids, bases and salts.
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Chemical Effects of Electric Current: Exploring Chemical Effects
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- Definition: The passage of an electric current through a conducting solution causes chemical reactions.
- The resulting effects are called the chemical effects of the electric current.
- Example: Two carbon rods / iron nails (electrodes), wrapped with copper wires, connected to a battery and immersed in salt water show some of the chemical effects of the electric current.
- It shows formation of bubbles of a gas on the electrodes, deposits of metal may be seen on electrodes or changes of colour of solutions may occur.
- The reaction would depend on what solution and electrodes are used.
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Electroplating: Electroplating Wonders for Protective and Aesthetic Coatings
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- Concept: The process of depositing a layer of any desired metal on another material by means of electricity is called ‘electroplating’.
- Common Application: It is one of the most common applications of chemical effects of electric current.
- Example: When 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.
- From the other electrode, a copper plate, an equal amount of copper gets dissolved in the solution.
- Thus, the loss of copper from the solution is restored and the process continues.
- This means that copper gets transferred from one electrode to the other.
- Industrial Use: Electroplating is widely used in industry for coating metal objects with a thin layer of a different metal.
- Example: Chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others.
- Use Of Chromium: Chromium has a shiny appearance and does not corrode. It resists scratches.
- However, chromium is expensive and it may not be economical to make the whole object out of chromium.
- So the object is made from a cheaper metal and only a coating of chromium over it is deposited.
- Electroplating of Jewellery: Jewellery makers electroplate silver and gold on less expensive metals.
- These ornaments have the appearance of silver or gold but are much less expensive.
- Use of Tin: Tin cans, used for storing food, are made by electroplating tin on iron. Tin is less reactive than iron.
- Thus, food does not come into contact with iron and does not spoil.
- Use of Iron: Iron is used in bridges and automobiles to provide strength.
- However, iron tends to corrode and rust.
- So, a coating of zinc is deposited on iron to protect it from corrosion and formation of rust.
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