8.1 Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal:
Pt(s) | Fe²⁺(aq), Fe³⁺(aq) || X⁺(aq) | X(s)
The cell potential of this cell was found to be 0,03 V - NSC Physical Sciences - Question 8 - 2018 - Paper 2
Question 8
8.1 Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal:
Pt(s) | Fe²⁺(aq), Fe³⁺(aq) || X⁺(aq) | X(s)
The cell pot... show full transcript
Worked Solution & Example Answer:8.1 Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal:
Pt(s) | Fe²⁺(aq), Fe³⁺(aq) || X⁺(aq) | X(s)
The cell potential of this cell was found to be 0,03 V - NSC Physical Sciences - Question 8 - 2018 - Paper 2
Step 1
8.1.1 Write down the type of electrochemical cell illustrated above.
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Answer
The electrochemical cell illustrated is a Galvanic (Voltaic) cell, which generates electrical energy from spontaneous chemical reactions.
Step 2
8.1.2 What does the single line (|) in the above cell notation represent?
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The single line (|) in the cell notation indicates a phase boundary or interface between different phases of the reactants.
Step 3
8.1.3 Write down the half-reaction that takes place at the anode in the above cell.
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Answer
At the anode, the oxidation half-reaction occurs:
ightarrow ext{Fe}^{3+} + e^-$$
Step 4
8.1.4 Identify X with the aid of a calculation.
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To identify X, we can use the given cell potential and the Nernst equation. From the data:
The cell potential Ecell=Eoxidation−Ereduction is 0.03 V.
Given Eoxidation for the Fe reaction is approximately 0.77 V. Thus:
0.03 = 0.77 - E_{red} \
E_{red} = 0.77 - 0.03 = 0.84 V$$
The equivalent reduction potential suggests that X corresponds to silver (Ag), since the standard reduction potential for Ag is approximately 0.80 V.
Step 5
8.2.1 Chemical symbol for the electrode in the cathode half-cell.
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The chemical symbol for the electrode in the cathode half-cell is Cu(s).
Step 6
8.2.2 NAME of the oxidising agent.
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The name of the oxidising agent in this reaction is Iron(III) ions (Fe³⁺).
Step 7
8.2.3 Overall balanced cell reaction that takes place in this cell.
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The overall balanced cell reaction can be written as:
