Question

Consider the cell \[\ce{Al | Al^{3+} (1 M) || Sn^{2+} (1 M) | Sn}\], \[\ce{E^0_{Al}}\] = −1.66 V; \[\ce{E^0_{Fe}}\] = −0.136 V, ∆G⁰ for the above cell is ____________.

Options

• −882 kJ

• −441 kJ

• −147 kJ

• −588 kJ

Answer 1

Consider the cell \[\ce{Al | Al^{3+} (1 M) || Sn^{2+} (1 M) | Sn}\], \[\ce{E^0_{Al}}\] = −1.66 V; \[\ce{E^0_{Fe}}\] = −0.136 V, ∆G0 for the above cell is −882 kJ.

Explanation:

\[\ce{Al -> Al^{3+} + 3e^-}\] ..............(i)

\[\ce{Sn^{2+} + 2e^- -> Sn}\] ..................(ii)

Multiply equation (i) by 2 and equation (ii) by 3

\[\ce{2Al -> 2Al^{3+} + 6e^-}\]

\[\ce{3Sn^{2+} + 6e^- -> 3Sn}\]

`"E"_"cell"^0 = "E"_"Sn"^0 - "E"_"Al"^0`

= (−0.136) − (−1.66)

= 1.524 V

∆G⁰ = −n F \[\ce{E^0_{cell}}\]

= −6 × 96500 × 1.524

= −882396 J

= −882 kJ