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CHEMISTRY FORM 2


1. STRUCTURE OF THE ATOM, AND THE PERIODIC TABLE
2. CHEMICAL FAMILIES AND PATTERNS IN PROPERTIES
3. CHEMICAL BONDING AND STRUCTURE
4. SALTS
5. EFFECT OF AN ELECTRIC CURRENT ON SUBSTANCES
6. CARBON AND SOME OF ITS COMPOUNDS
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Effect of an electric current on substances: Applications of electrolysis

5.0 Effect of an electric current on substances


5.5.Applications of electrolysis


  1. Extraction of metals

  2. Purification of metals

  3. Electroplating of items such as utensils and cutleries.


Electroplating uses metals that retain their attractive appearance for long. Such metals protect other items from chemical attack. The electrolyte used in electroplating must contain ions of the metal (e.g. Cu2+ and Ag+) to be used in coating the item. The item itself is made one of the electrodes. Figure 5.5 shows examples of items already electroplated using copper and silver.


Electroplated items, high school chemistry

Figure 5.5 Electroplated items


Questions 5.5

  1. Are the metals used to electroplate other items reactive or unreactive? Explain your answer.

  2. Should the item to be electroplated be made the anode or cathode? Explain your answer.

  3. From your knowledge of electrolysis, must electroplated item be a conductor of electricity? Explain.

  4. Draw a fully labelled circuit diagram to show how you would electroplate a graphite rod using a battery of two electric cells, aqueous copper (II) sulphate solution as electrolyte and copper metal as anode. Represent an electric cell with the conventional symbol.


Answers to Questions 5.5


Project 5


Use the set-up in the answer to Question 4 of Questions 5.5 to electroplate a graphite rod. The electrolyte is copper (II) sulphate solution. Also, find out whether the electrodes should be held closer together or farther apart. Write a report explaining what you have done and the results obtained.