Question

Consider the following E° values:

\[\ce{E^{\circ}_{{Fe^{3+}/{Fe^{2+}}}}}\] = + 0.77 V

\[\ce{E^{\circ}_{{Sn^{2+}/{Sn}}}}\] = −0.14 V.

Under standard conditions the potential for the reaction:

\[\ce{Sn_{(s)} +  2Fe^{3+}_{ (aq)} -> 2Fe^{2+}_{ (aq)} + Sn^{2+}_{ (aq)}}\] is:

Options

• 1.68 V

• 1.40 V

• 0.91 V

• 0.63 V

Answer 1

0.91 V

Explanation:

Given: \[\ce{E^{\circ}_{{Fe^{3+}/{Fe^{2+}}}}}\] = + 0.77 V

\[\ce{E^{\circ}_{{Sn^{2+}/{Sn}}}}\] = −0.14 V

\[\ce{E{^{\circ}_{cell}} = E{^{\circ}_{oxd}} - E{^{\circ}_{red}}}\]

∴ \[\ce{E{^{\circ}_{cell}}}\] = 0.77 − (−0.14)

∴ \[\ce{E{^{\circ}_{cell}}}\] = 0.91 V