SSCE VCE Chemistry Production of Chemicals Using Electrolysis: The simplified diagram below sho

The simplified diagram below shows the Hall Cell that is used for the industrial production of aluminium - VCE - SSCE Chemistry - Question 6 - 2006 - Paper 1

Question 6

The simplified diagram below shows the Hall Cell that is used for the industrial production of aluminium. **a.** In circles X and Y in the diagram, show the polarit... show full transcript

Worked Solution & Example Answer:The simplified diagram below shows the Hall Cell that is used for the industrial production of aluminium - VCE - SSCE Chemistry - Question 6 - 2006 - Paper 1

Step 1

In circles X and Y in the diagram, show the polarity of the electrodes.

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Answer

In circle X, show the positive polarity (+) for the anode, and in circle Y, show the negative polarity (-) for the cathode.

Step 2

In the Hall Cell, the electrolyte consists of alumina mixed with another compound. In box Z, write the name or the formula of this compound.

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Answer

The compound is cryolite, which can be represented chemically as Na₃AlF₆.

Step 3

Write a half equation for the reaction that occurs at the anode.

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Answer

At the anode, the oxidation half-reaction is:

$C + 2O^{2-} \rightarrow CO_2 + 4e^-$

Step 4

Write a half equation for the reaction that occurs at the cathode.

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Answer

At the cathode, the reduction half-reaction is:

$Al^{3+} + 3e^- \rightarrow Al$

Step 5

Suppose the electrolyte was replaced with an aqueous solution of Al(NO₃)₃ at 25°C. Write an equation for the half reaction that would occur at the cathode.

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Answer

The half reaction at the cathode would be:

$Al^{3+} + 3e^- \rightarrow Al$

The simplified diagram below shows the Hall Cell that is used for the industrial production of aluminium - VCE - SSCE Chemistry - Question 6 - 2006 - Paper 1

Worked Solution & Example Answer:The simplified diagram below shows the Hall Cell that is used for the industrial production of aluminium - VCE - SSCE Chemistry - Question 6 - 2006 - Paper 1

In circles X and Y in the diagram, show the polarity of the electrodes.

In the Hall Cell, the electrolyte consists of alumina mixed with another compound. In box Z, write the name or the formula of this compound.

Write a half equation for the reaction that occurs at the anode.

Write a half equation for the reaction that occurs at the cathode.

Suppose the electrolyte was replaced with an aqueous solution of Al(NO₃)₃ at 25°C. Write an equation for the half reaction that would occur at the cathode.

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