8.1 A piece of zinc (Zn) is placed in a test tube containing an acidified permanganate solution, MnO₄⁻ (aq) - NSC Physical Sciences - Question 8 - 2022 - Paper 2
Question 8
8.1 A piece of zinc (Zn) is placed in a test tube containing an acidified permanganate solution, MnO₄⁻ (aq). After some time, it is found that a redox reaction has t... show full transcript
Worked Solution & Example Answer:8.1 A piece of zinc (Zn) is placed in a test tube containing an acidified permanganate solution, MnO₄⁻ (aq) - NSC Physical Sciences - Question 8 - 2022 - Paper 2
Step 1
Write down the NAME or FORMULA of the reducing agent.
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Answer
The reducing agent in this reaction is zinc, represented as Zn or zinc metal.
Step 2
Refer to the relative strengths of the OXIDISING AGENTS to explain why a redox reaction has taken place.
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Answer
In the context of this reaction, the permanganate ion (MnO₄⁻) acts as a stronger oxidizing agent compared to the zinc ions (Zn²⁺). This means that MnO₄⁻ can oxidize Zn to Zn²⁺ while being reduced itself to Mn²⁺. The tendency of MnO₄⁻ to accept electrons is greater than that of Zn, facilitating the redox process.
Step 3
Write down the function of component Y.
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Component Y provides a path for the movement of ions, completing the circuit and ensuring electrical neutrality in the cell.
Step 4
In which direction will electrons flow in the external circuit? Choose from 'Ni to Mn' OR 'Mn to Ni'.
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Electrons will flow from Ni to Mn in the external circuit.
Step 5
Calculate the initial emf of this cell.
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The initial emf (E°) can be calculated using the standard reduction potentials of the half reactions. The equation is:
E°cell=E°cathode−E°anode
For this cell:
E°_{cell} = 0.91 V - (-0.27 V) = 0.91 V + 0.27 V = 1.18 V.
Step 6
Write down the balanced equation for the net cell reaction taking place.
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Answer
The balanced cell reaction can be expressed as:
Zn(s)+2MnO4−(aq)+16H+(aq)→2Mn2+(aq)+Zn2+(aq)+8H2O(l)
Step 7
Will the reading on the voltmeter INCREASE, DECREASE or REMAIN THE SAME?
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The reading on the voltmeter will INCREASE. Increasing the concentration of Ni²⁺ enhances the driving force of the reaction, thus increasing the cell potential.
