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
DC source
X
Y
concentra... 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 type of electrochemical cell illustrated is an ELECTROLYTIC cell. This is because it involves the use of a DC source to drive a non-spontaneous reaction.
Step 2
9.2 Write down the half-reaction that takes place at electrode Q.
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At electrode Q, the half-reaction is:
ightarrow H_2 + 2OH^-$$
Step 3
9.3 The products formed in the two cells are compared.
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In comparing the products formed in both cells, we find that hydrogen gas is produced in both cells.
Step 4
9.3.1 Name ONE substance that is produced in BOTH cells.
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Answer
One substance that is produced in both cells is Chlorine gas (Cl2).
Step 5
9.3.2 Write down the LETTERS of the TWO electrodes where this product is formed. Choose from P, Q, X and Y.
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The letters of the two electrodes where chlorine gas is produced are P and Y.
Step 6
9.5 Is electrode X the CATHODE or the ANODE? Give a reason for your answer.
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Electrode X is the ANODE. This is because oxidation occurs at the anode during electrolysis, and in this cell, electrode X loses electrons.
