Chlorine is produced industrially by the electrolysis of a concentrated sodium chloride solution, NaCl(aq) - NSC Physical Sciences - Question 9 - 2019 - Paper 2
Question 9
Chlorine is produced industrially by the electrolysis of a concentrated sodium chloride solution, NaCl(aq).
The balanced equation for the net (overall) cell reactio... show full transcript
Worked Solution & Example Answer:Chlorine is produced industrially by the electrolysis of a concentrated sodium chloride solution, NaCl(aq) - NSC Physical Sciences - Question 9 - 2019 - Paper 2
Step 1
Define the term electrolysis.
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Answer
Electrolysis is the chemical process in which electrical energy is converted to chemical energy. It involves using electrical energy to trigger a chemical change by passing an electric current through a solution or molten ionic compound.
Step 2
9.2.1 Half-reaction that takes place at the cathode.
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Answer
At the cathode, the half-reaction is as follows:
2H2O(l)+2e−→H2(g)+2OH−(aq)
Step 3
9.2.2 NAME or FORMULA of the oxidising agent.
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The oxidising agent is Cl<sub>2</sub>.
Step 4
9.3 Refer to the Table of Standard Reduction Potentials to explain why sodium ions are not reduced during this process.
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Answer
Sodium ions (Na<sup>+</sup>) do not get reduced because their reduction potential is lower than that of water. The standard reduction potential for the half-reaction involving the reduction of sodium is +2.71 V, while that for the reduction of water is +0.82 V. Therefore, water is a stronger oxidising agent than sodium ions in this reaction context, leading to the preferential reduction of water instead of sodium ions.
