The diagrams below represent two electrochemical cells - NSC Physical Sciences - Question 9 - 2019 - Paper 2
Question 9
The diagrams below represent two electrochemical cells.
P, Q, X and Y are carbon electrodes.
Cell A
[P]
|
|
[Q]
concentrated NaCl(aq)
Cell B
[X] ... show full transcript
Worked Solution & Example Answer:The diagrams below represent two electrochemical cells - NSC Physical Sciences - Question 9 - 2019 - Paper 2
Step 1
9.1 What type of electrochemical cell, GALVANIC or ELECTROLYTIC, is illustrated above?
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Answer
The electrochemical cell illustrated is an ELECTROLYTIC cell, as it requires an external DC source to drive the reaction.
Step 2
9.2 Write down the half-reaction that takes place at electrode Q.
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Answer
At electrode Q, the half-reaction taking place can be represented as:
2H2O+2e−→H2+2OH−
This reaction indicates the reduction of water to hydrogen gas.
Step 3
9.3 The products formed in the two cells are compared.
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9.3.1 One substance that is produced in BOTH cells is Chlorine gas (Cl2).
9.3.2 The letters of the two electrodes where this product is formed are Q and Y.
Step 4
9.4 Is electrode X the CATHODE or the ANODE? Give a reason for your answer.
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Answer
Electrode X is the CATHODE. This is because it is where the reduction reaction occurs, gaining electrons from the external circuit.
