Question

A galvanic cell with E o cell = 0.30 V can be constructed using an iron electrode in a 1.0 M Fe(NO3)2 solution, and either a tin electrode in a 1.0 M Sn(NO3)2 solution, or a chromium electrode in a 1.0 M Cr(NO3)3 solution even though Sn2+/Sn and Cr3+/Cr have different reduction potentials. Give the overall balanced reaction for Fe-Sn cell. Do not include the states of matter.

Answer 1

Answer: The half reactions are written below.

Explanation:

Oxidation reaction is defined as the reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.

$X\rightarrow X^{n+}+ne^-$

Reduction reaction is defined as the reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

$X^{n+}+ne^-\rightarrow X$

We are given a chemical cell which is Fe-Sn cell. The half reaction follows:

Oxidation half reaction:  $Fe\rightarrow Fe^{2+}+2e^-;E^o_{Fe^{2+}/Fe}=-0.44V$

Reduction half reaction:  $Sn^{2+}+2e^-\rightarrow Sn;E^o_{Sn^{2+}/Sn}=-0.14V$

The substance having highest positive $E^o$ potential will always get reduced and will undergo reduction reaction. Here, zinc will always undergo reduction reaction will get reduced.

Total cell reaction: $Fe+Sn^{2+}\rightarrow Fe^{2+}+Sn$

Hence, the half reactions are written above.