In the electrochemical cell below, carbon electrodes are used during the electrolysis of a concentrated sodium chloride solution - NSC Physical Sciences - Question 9 - 2016 - Paper 2
Question 9
In the electrochemical cell below, carbon electrodes are used during the electrolysis of a concentrated sodium chloride solution.
The balanced equation for the net ... show full transcript
Worked Solution & Example Answer:In the electrochemical cell below, carbon electrodes are used during the electrolysis of a concentrated sodium chloride solution - NSC Physical Sciences - Question 9 - 2016 - Paper 2
Step 1
Is the reaction EXOTHERMIC or ENDOTHERMIC?
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Answer
The reaction is ENDOTHERMIC. This is because energy is absorbed in the form of heat during the electrolysis process as it breaks bonds to form products.
Step 2
Is electrode P the ANODE or the CATHODE? Give a reason for the answer.
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Electrode P is the ANODE. This is because it is connected to the positive terminal of the battery where oxidation occurs.
Step 3
NAME or FORMULA of gas X
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Answer
Chlorine gas is gas X, with the formula (Cl_2).
Step 4
NAME or FORMULA of gas Y
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Hydrogen gas is gas Y, with the formula (H_2).
Step 5
Is the solution in the cell ACIDIC or ALKALINE (BASIC) after completion of the reaction? Give a reason for the answer.
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The solution is ALKALINE (BASIC) after completion of the reaction. This is because hydroxide ions (OH^-(aq)) are produced during the discharge of water at the cathode, increasing the pH of the solution.
