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NTA Abhyas JEE Main2020Chemistryp Block Elements (Group 13 & 14)Practice

In the context of the Hall-Heroult process for the extraction of Al, which of the following statements is false ?

Options

  1. ACO and C O 2 are produced in this process
  2. BA l 2 O 3 is mixed with C a F 2 which lowers the melting point of the mixture and brings conductivity
  3. CA l 3 + is reduced at the cathode to form Al
  4. DN a 3 A l F 6 helps in increasing the melting point of the mixture

Correct answer

D. N a 3 A l F 6 helps in increasing the melting point of the mixture

Step-by-step solution

Hall heroult process: In the Hall-Héroult process the following simplified reactions take place at the carbon electrodes: Cathode: A l 3 + + 3 e - 1 → A l Anode: O 2 - + C → C O + 2 e - Overall: A l 2 O 3 + 3 C → 2 A l + 3 C O And 2 A l 2 O 3 + 3 C → 4 A l + 3 C O 2 In reality, much more C O 2 is formed at the anode than C O : Cryolite ( N a 3 A l F 6 ) lowers the melting point of the mixture and make it more conductive in nature so as to carry out electrolysis of the ore in Hall-Heroult process.

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