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An electrochemical cell consists of a half-cell containing V^{3+}(aq) and V^{2+}(aq) ions and another half-cell containing VO^{2-}(aq) and VO^{3-}(aq) ions - CIE - A-Level Chemistry - Question 4 - 2017 - Paper 1
Question 4
An electrochemical cell consists of a half-cell containing V^{3+}(aq) and V^{2+}(aq) ions and another half-cell containing VO^{2-}(aq) and VO^{3-}(aq) ions. (i) Use... show full transcript
Worked Solution & Example Answer:An electrochemical cell consists of a half-cell containing V^{3+}(aq) and V^{2+}(aq) ions and another half-cell containing VO^{2-}(aq) and VO^{3-}(aq) ions - CIE - A-Level Chemistry - Question 4 - 2017 - Paper 1
Step 1
Use data from the Data Booklet to calculate a value for the E^{ullet}_{cell}:
Answer
To calculate the standard cell potential, we use the formula:
E^{ullet}_{cell} = E^{ullet}_{cathode} - E^{ullet}_{anode}
From the Data Booklet, let's assume:
- For the reduction of VO^{2-} to VO^{3-}: E^{ullet}_{cathode} = 1.00 V
- For the reduction of V^{3+} to V^{2+}: E^{ullet}_{anode} = -0.26 V
Plugging in these values gives:
E^{ullet}_{cell} = 1.00 - (-0.26) = 1.26 ext{ V}
Step 2
Step 3
Draw a fully labelled diagram of the apparatus you could use to measure the potential of this cell. Include the necessary chemicals.
Answer
To measure the potential of the electrochemical cell, a diagram would include:
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Two half-cells with appropriate labels:
- One half-cell containing V^{3+}(aq) and V^{2+}(aq) ions.
- The other half-cell containing VO^{2-}(aq) and VO^{3-}(aq) ions.
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A salt bridge connecting the two half-cells to allow ion flow.
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A voltmeter connected to measure the potential difference.
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Platinum electrodes in each half-cell to conduct electricity.
Each solution should be adequately labelled to indicate its composition.