Explain how the salt bridge provides an electrical connection between the two solutions - AQA - A-Level Chemistry - Question 6 - 2018 - Paper 1
Question 6
Explain how the salt bridge provides an electrical connection between the two solutions.
The salt bridge has mobile ions that can move through it, allowing for the ... show full transcript
Worked Solution & Example Answer:Explain how the salt bridge provides an electrical connection between the two solutions - AQA - A-Level Chemistry - Question 6 - 2018 - Paper 1
Step 1
Explain how the salt bridge provides an electrical connection between the two solutions.
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Answer
The salt bridge has mobile ions that can move through it, allowing for the flow of charge. This movement of ions does not allow electrons to travel through the bridge; rather, it maintains electrical neutrality in both half-cells by balancing the charge as the reactions occur.
Step 2
Calculate the electrode potential of the left-hand electrode in Figure 2.
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Answer
The electrode potential for the left-hand electrode can be calculated using the equation:
Ecell​=Eright​−Eleft​
Where:
Ecell​=+0.16 V
Eright​=+0.34 V
Thus, we rearrange to find:
Eleft​=Eright​−Ecell​=+0.34 V−+0.16 V=+0.18 V
Step 3
State why the left-hand electrode does not have an electrode potential of +0.34 V.
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Answer
The left-hand electrode does not have an electrode potential of +0.34 V because the concentration of Cu extsuperscript{2+} ions in the left half-cell is significantly different from that needed to achieve this potential.
Step 4
Give the conventional representation for the cell in Figure 2.
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Answer
The conventional representation of the cell is:
Cu(s)∣Cu2+(aq,0.15 mol dm−3)∣∣Cu2+(aq,1.0 mol dm−3)∣Cu(s)
Step 5
Suggest how the concentration of copper(II) ions in the left-hand electrode changes when the bulb is alight. Give one reason why the EMF of the cell decreases to 0 V.
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Answer
The concentration of copper(II) ions in the left-hand electrode increases as copper dissolves from the anode. The EMF of the cell decreases to 0 V because the concentrations of Cu extsuperscript{2+} ions in the two solutions become equal, resulting in no further potential difference.
