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Class 8 - Science

Chemical Effects of Electric Current


Recall 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 sliver 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 tty doing It ourselves.When electric current is assed 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. But what about the loss of copper from the solution? From the other electrode, a copper plate, an equal amount of copper gets dissolved in the solution. Thus, the 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. Electroplating is a very useful process. It Is widely used In Industry for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which the metal of the object lacks. For example, chromiumplating Is done on many objects such as car parts, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others. Chromium has a shiny appearance. It 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. Jewellery makers electroplate sliver and gold on less expensive metals. These ornaments have the appearance of silver or gold but are much less expensive. 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. 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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Chemical Effects of Electric Current - Notes
1. Do Liquids Conduct Electricity?
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2. Chemical Effects of Electric Current
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3. Electroplating
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