Problem 45 State the reactions that take pl... [FREE SOLUTION]

Chapter 8: Problem 45

State the reactions that take place at the cathode and anode during the process of electrolytic reduction of alumina.

Short Answer

Expert verified

Answer: During the electrolytic reduction of alumina, the reduction of aluminum ions takes place at the cathode, which can be represented by the equation: Al^{3+} + 3e^- -> Al. At the anode, the oxidation of oxide ions occurs, producing oxygen gas and combining with the carbon anodes to form carbon dioxide gas. This can be represented by the equations: 2 O^{2-} -> O2 + 4e^- and C + O2 -> CO2.

Step by step solution

Identify the cathode and anode

During electrolytic reduction of alumina, the cathode is a container made of graphite (carbon) where the reduction reaction will take place, and the anode is made of consumable carbon rods where the oxidation reaction will occur.

Reaction at the cathode

As alumina (Al2O3) is dissolved in molten cryolite (Na3AlF6), it breaks down into its ions 鈥� aluminum ions (Al^{3+}) and oxide ions (O^{2-}). At the cathode, the reduction of aluminum ions will take place as they gain electrons to form aluminum metal. The reaction at the cathode can be represented by the following equation: Al^{3+} + 3e^- -> Al

Reaction at the anode

At the anode, the oxidation of oxide ions will take place as they lose electrons to form oxygen gas. Here, the oxide ions combine with the carbon anodes to produce carbon dioxide gas. The reaction at the anode can be represented by the following equation: 2 O^{2-} -> O2 + 4e^- C + O2 -> CO2 These reactions together produce aluminum metal and carbon dioxide gas during the electrolytic reduction of alumina.

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91影视

State the reactions that take place at the cathode and anode during the process of electrolytic reduction of alumina.

Short Answer

Step by step solution

Identify the cathode and anode

Reaction at the cathode

Reaction at the anode

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