The diagram shows a Downs cell used to electrolyse molten sodium chloride - Leaving Cert Chemistry - Question B - 2016
Question B
The diagram shows a Downs cell used to electrolyse molten sodium chloride.
(i) Give one everyday application for each product of this electrolysis.
(ii) Why must t... show full transcript
Worked Solution & Example Answer:The diagram shows a Downs cell used to electrolyse molten sodium chloride - Leaving Cert Chemistry - Question B - 2016
Step 1
Give one everyday application for each product of this electrolysis.
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Answer
The products of the electrolysis of molten sodium chloride are sodium (Na) and chlorine (Cl₂).
Sodium (Na): Used in street lighting and as a desiccant in various chemical processes.
Chlorine (Cl₂): Commonly used in water treatment to disinfect and kill microorganisms.
Step 2
Why must the electrolyte be molten?
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Answer
The electrolyte, molten sodium chloride, must be molten because it conducts electricity only in this state. In solid form, sodium chloride cannot conduct electricity due to the rigid ionic structure that prevents the movement of ions.
Step 3
What is the function of the steel mesh?
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Answer
The steel mesh serves to prevent the recombination of the products (sodium and chlorine) by keeping them separate during the electrolysis process. This ensures that each product is collected efficiently without mixing.
Step 4
Write a balanced equation for the cell reaction.
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Answer
The balanced equation for the cell reaction in the Downs cell is:
ightarrow ext{Na (l)} + ext{Cl}_2 (g)$$
Step 5
Why is electrolysis the method of choice for the extraction of aluminium from its ores?
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Electrolysis is preferred for extracting aluminium due to its position in the electrochemical series, where it is more reactive and does not reduce easily. Other chemical reducing agents are not capable of reducing aluminium oxide efficiently, making electrolysis the most effective method.
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