In the electrochemical cell shown below an aluminium electrode and another metal electrode, Y, are used - NSC Physical Sciences - Question 8 - 2017 - Paper 2
Question 8
In the electrochemical cell shown below an aluminium electrode and another metal electrode, Y, are used.
It is found that the mass of the aluminium electrode increa... show full transcript
Worked Solution & Example Answer:In the electrochemical cell shown below an aluminium electrode and another metal electrode, Y, are used - NSC Physical Sciences - Question 8 - 2017 - Paper 2
Step 1
8.1.1 Name of component Q
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Answer
The name of component Q is the salt bridge.
Step 2
8.1.2 Type of electrochemical cell represented above
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The type of electrochemical cell represented is a Voltaic or Galvanic cell.
Step 3
8.2.1 The concentration of Al$^{3+}$ (aq)
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Answer
The concentration of Al3+ (aq) will DECREASE while the cell is functioning.
Step 4
8.2.2 The concentration of Y$^{2+}$ (aq)
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The concentration of Y2+ (aq) will INCREASE while the cell is functioning.
Step 5
8.3.1 Half-reaction that takes place at electrode Y
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The half-reaction that takes place at electrode Y is:
Y(s) → Y2+ (aq) + 2e−.
Step 6
8.3.2 Cell notation of the cell
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The cell notation of the cell is:
Y(s) | Y2+ (aq) || Al3+ (aq) | Al(s).
Step 7
8.4 Identify metal Y by means of a calculation
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Answer
To identify metal Y, use the standard cell potential formula:
Ecell=Eoxidation−Ereduction
We know the standard cell potential (Eo) is 0.7 V. By calculating using standard reduction potentials from the data sheet, we can find that Y is Mg (with Eo = -2.36 V).
