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Electrochemistry and electrolysis.

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Introduction

Electrochemistry USING an electric current to produce chemical changes is called electrolysis. It is often used to purify metals and other substances. An electric circuit is set up using two electrodes, an electrolyte (a liquid containing ions), and a source of electricity. When the electricity is on, ions in the electrolyte move towards the electrodes. There, they gain or lose electrons, making them - and the electrodes - chemically different. Chemical changes can also produce electricity. A battery consists of an electrolyte between two different metal electrodes. Chemical reactions occur between the electrodes and the ions in the electrolyte, making electrons flow. PURIFYING COPPER If a current is passed through copper sulphate solution, positive copper ions move from the impure copper anode to the cathode, where they are deposited as pure copper metal. ...read more.

Middle

metal The element copper is a lustrous reddish-brown transition metal. It is malleable and ductile, and is a good conductor of electricity. It was first used about 5,000 years ago in the form of bronze (an alloy of copper and tin) to make tools, but was later replaced by iron. It has also been used in coins, and today is used in electrical cables, wires, and other components, and also in plumbing. Properties and Uses The reddish-brown colour of copper is due to a thin film of oxide, and when the film is removed the colour of the pure metal is rosy pink. It is an extremely tough metal, and can be drawn out into a thin wire or hammered into a thin leaf. ...read more.

Conclusion

It may be combined with a number of other metals to make a wide range of useful alloys. Electrolysis This method is sometimes used for extracting copper from the ore, but is usually employed as a means of refining the already purified metal. Commercial copper refined in this way is one of the purest commercial metals, with a purity of about 99.9 per cent. Ingots of the unrefined metal are placed in copper sulphate, and these form the anodes, while sheets of pure copper function as cathodes. As a current is passed through the solution, the anode is eaten away and pure copper is deposited at the cathodes. The impurities pass into solution, unless they are silver and gold, which settle as slime on the bottom of the tank and can be recovered. ...read more.

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