The cell notation Zn(s)|Zn^2+(aq)|Cu^2+(aq)|Cu(s) represents a galvanic cell operating under standard conditions - NSC Technical Sciences - Question 6 - 2020 - Paper 2
Question 6
The cell notation Zn(s)|Zn^2+(aq)|Cu^2+(aq)|Cu(s) represents a galvanic cell operating under standard conditions.
6.1.1 Define the term galvanic cell.
6.1.2 Draw a... show full transcript
Worked Solution & Example Answer:The cell notation Zn(s)|Zn^2+(aq)|Cu^2+(aq)|Cu(s) represents a galvanic cell operating under standard conditions - NSC Technical Sciences - Question 6 - 2020 - Paper 2
Step 1
Define the term galvanic cell.
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Answer
A galvanic cell is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells connected by a salt bridge or a porous membrane.
Step 2
Draw a labelled diagram to represent the Zn-Cu cell. Show the direction of electron flow in the external circuit.
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Answer
The diagram of the Zn-Cu galvanic cell should include elements accurately labeled: the anode (Zn electrode in ZnSO₄ solution), the cathode (Cu electrode in CuSO₄ solution), a voltmeter indicating the voltage (showing e⁻ flow from anode to cathode), and a salt bridge. Arrows should indicate the direction of electron flow from the anode to the cathode.
Step 3
Write down TWO standard conditions under which the Zn-Cu cell operates.
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Answer
Temperature of 25°C (298 K).
Concentration of electrolytes: 1 mol·dm⁻³.
Step 4
To which half-cell do the anions in the salt bridge migrate?
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Answer
The anions in the salt bridge migrate towards the zinc half-cell.
Step 5
Explain the answer to QUESTION 6.1.4.
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Answer
Anions migrate toward the zinc half-cell because the zinc anode dissolves into the solution, producing Zn²⁺ ions. To maintain charge neutrality in the half-cell, anions from the salt bridge must move towards it.
Step 6
Identify electrode X by means of a calculation.
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Answer
Using the standard electrode potential values, if E°cell = E°cathode - E°anode, and given that E°cell = 2.00 V, the calculated electrode potential indicates that electrode X is likely aluminum (Al).
Step 7
Write down the half-reaction taking place at the anode.
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Answer
At the anode, the half-reaction can be expressed as:
ightarrow ext{Al}^{3+} + 3e^-$$
Step 8
Which electrode will experience a decrease in mass?
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The anode (electrode X) will experience a decrease in mass as it loses material to form ions in solution.
Step 9
Explain the answer to QUESTION 6.2.3.
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As the anode (X) undergoes oxidation, it loses electrons and will corrode, resulting in a decrease in its overall mass. This is a typical behavior for electrodes undergoing oxidation in electrochemical cells.
