(D) In the Hall-Heroult process,pure $Al_2O_3$ is mixed with $Na_3AlF_6$ (cryolite) and $CaF_2$ (fluorspar) to lower the melting point and increase el

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(D) In the Hall-Heroult process,pure $Al_2O_3$ is mixed with $Na_3AlF_6$ (cryolite) and $CaF_2$ (fluorspar) to lower the melting point and increase electrical conductivity. At the cathode,$Al^{3+}$ ions are reduced to $Al$ metal: $Al^{3+} + 3e^- \rightarrow Al$. At the anode,oxygen gas is evolved,which reacts with the graphite anode to form $CO_2$: $C(s) + O_2(g) \rightarrow CO_2(g)$. Therefore,all the given statements are correct.

Class 12 Chemistry General Principles and Processes of Isolation of Elements Mix Examples of General Principles and processes of Isolation of Elements

Medium

In the electrolysis of $Al_2O_3$ by the Hall-Heroult process,which of the following statements is correct?

A
Cryolite $(Na_3AlF_6)$ lowers the melting point of $Al_2O_3$ and increases its electrical conductivity.
B
$Al$ is obtained at the cathode and $O_2$ at the anode.
C
Graphite anode is converted into $CO_2$.
D
All of these.