A galvanic cell is constructed from the following two half cells under standard conditions - VCE - SSCE Chemistry - Question 7 - 2008 - Paper 1
Question 7
A galvanic cell is constructed from the following two half cells under standard conditions.
Half cell 1: a nickel electrode in a solution of 1.0 M nickel nitrate
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Worked Solution & Example Answer:A galvanic cell is constructed from the following two half cells under standard conditions - VCE - SSCE Chemistry - Question 7 - 2008 - Paper 1
Step 1
Given that the standard reduction potential of Cd^{2+}(aq) / Cd(s) is -0.40V, show on the above sketch the direction in which electrons will flow in the external circuit of this galvanic cell.
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Answer
In a galvanic cell, electrons flow from the anode to the cathode. In this case, since Cd(s) has a higher standard reduction potential than Ni(s), the nickel half-cell will serve as the anode where oxidation occurs. Therefore, electrons will flow from the nickel electrode (Ni) to the cadmium electrode (Cd) in the external circuit.
Step 2
Give the equation for the half reaction that takes place at the anode of this cell.
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Answer
The half-reaction that takes place at the anode of this cell can be represented as:
Ni2+(aq)+2e−→Ni(s)
This shows that nickel ions in solution gain electrons at the anode to form nickel metal.
Step 3
List two factors that need to be considered when selecting an appropriate substance for use in the salt bridge.
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Answer
The substance must be soluble in water to ensure effective ionic migration.
It should not react with the components in the half-cells, ensuring no precipitate forms that could impede ion flow.