Part 3 Determining Standard Reduction Potentials You will prepare three half-cel

Question

Part 3 Determining Standard Reduction Potentials You will prepare three half-cells of the form M (s) I M2+ (aq) where M Zn, Pb and Cu For each, the counter ion is NO3 at a concentration of 0.050 M You will now construct three different voltaic cells, using the below combinations of half cells Zn/Cu Zn/Pb and Pb/Cu By measuring the voltage of each cell you can determine the electrical potential of the half-cells relative to each other. Since this involves three half-reactions and three cell voltages, there are three relationships and three unknowns. You will therefore be given one of the cell voltages as an initial starting point.

Explanation / Answer

for the first cell,

Sr l Sr2+ (0.1M) ll Ni2+ (0.1M) l Ni

Here,

Sr is anode and Ni is cathode.

The reduction potential is given by cathode and oxidation potential is given by anode

We know,

Ecell = Ecathode - Eanode

2.643 = Eni - Esr

2.643 = Eni - (-2.9)

Eni = Ecathode = reducing potential of cathode = -0.257V

for the second cell,

Sr l Sr2+ (0.1M) ll Pt2+ (0.1M) l Pt

Here,

Sr is anode and Pt is cathode.

The reduction potential is given by cathode and oxidation potential is given by anode

We know,

Ecell = Ecathode - Eanode

4.088 = Ept - Esr

4.088 = Ept - (-2.9)

Ept = Ecathode = reducing potential of cathode = 1.188V

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