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An iron wire is immersed in a solution c...

An iron wire is immersed in a solution containing `ZnSO_(4) and NiSO_(4)`. When the concentration of each salt is 1 M, predict giving reactions which of the following reactions is likely to proceed : (i) Iron reduces `Zn^(+)` ions (ii) Iron reduces `Ni^(2+)` ions.
Given
`E^(Theta)= -0.76 V " for "Zn^(2+)//Zn`
`E^(Theta)= -0.44 V" for "Fe^(2+)//Fe`
`E^(Theta)= -0.25V " for "Ni^(2+)//Ni`

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The correct Answer is:
To solve the problem of whether iron can reduce \( Zn^{2+} \) ions or \( Ni^{2+} \) ions when immersed in a solution of \( ZnSO_4 \) and \( NiSO_4 \), we will analyze the standard reduction potentials given for each half-reaction. ### Step-by-Step Solution: 1. **Identify the half-reactions and their standard reduction potentials**: - For \( Zn^{2+} + 2e^- \rightarrow Zn \), \( E^\circ = -0.76 \, V \) - For \( Ni^{2+} + 2e^- \rightarrow Ni \), \( E^\circ = -0.25 \, V \) - For \( Fe^{2+} + 2e^- \rightarrow Fe \), \( E^\circ = -0.44 \, V \) 2. **Determine the oxidation and reduction reactions**: - When iron (Fe) is immersed in the solutions, it can either oxidize (lose electrons) or reduce (gain electrons). - The oxidation half-reaction for iron is: \[ Fe \rightarrow Fe^{2+} + 2e^- \] - The reduction half-reactions are: - For zinc: \[ Zn^{2+} + 2e^- \rightarrow Zn \] - For nickel: \[ Ni^{2+} + 2e^- \rightarrow Ni \] 3. **Calculate the cell potentials for both reactions**: - **For the reaction with \( Zn^{2+} \)**: - Anode (oxidation): \( Fe \rightarrow Fe^{2+} + 2e^- \) (oxidation potential = \( +0.44 \, V \)) - Cathode (reduction): \( Zn^{2+} + 2e^- \rightarrow Zn \) (reduction potential = \( -0.76 \, V \)) - Calculate \( E^\circ_{cell} \): \[ E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = (-0.76) - (-0.44) = -0.32 \, V \] - Since \( E^\circ_{cell} < 0 \), this reaction is not feasible. - **For the reaction with \( Ni^{2+} \)**: - Anode (oxidation): \( Fe \rightarrow Fe^{2+} + 2e^- \) (oxidation potential = \( +0.44 \, V \)) - Cathode (reduction): \( Ni^{2+} + 2e^- \rightarrow Ni \) (reduction potential = \( -0.25 \, V \)) - Calculate \( E^\circ_{cell} \): \[ E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = (-0.25) - (-0.44) = 0.19 \, V \] - Since \( E^\circ_{cell} > 0 \), this reaction is feasible. 4. **Conclusion**: - Iron cannot reduce \( Zn^{2+} \) ions because the cell potential is negative. - Iron can reduce \( Ni^{2+} \) ions because the cell potential is positive. ### Final Answer: - (i) Iron does not reduce \( Zn^{2+} \) ions. - (ii) Iron reduces \( Ni^{2+} \) ions.

To solve the problem of whether iron can reduce \( Zn^{2+} \) ions or \( Ni^{2+} \) ions when immersed in a solution of \( ZnSO_4 \) and \( NiSO_4 \), we will analyze the standard reduction potentials given for each half-reaction. ### Step-by-Step Solution: 1. **Identify the half-reactions and their standard reduction potentials**: - For \( Zn^{2+} + 2e^- \rightarrow Zn \), \( E^\circ = -0.76 \, V \) - For \( Ni^{2+} + 2e^- \rightarrow Ni \), \( E^\circ = -0.25 \, V \) - For \( Fe^{2+} + 2e^- \rightarrow Fe \), \( E^\circ = -0.44 \, V \) ...
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