The standard emf for the cell using the overall cell reaction below is +2.20 V:
2Al(s) + 3I2(s) → 2Al3+(aq) + 6I-(aq)
The emf generated by the cell when [Al3+] = 4.5 × 10-3 M and [I-] = 0.15 M is ________ V.

(A) 2.23
(B) 2.20
(C) 2.39
(D) 2.32
(E) 2.10

Respuesta :

Answer:

emf generated by cell is 2.32 V

Explanation:

Oxidation: [tex]2Al-6e^{-}\rightarrow 2Al^{3+}[/tex]

Reduction: [tex]3I_{2}+6e^{-}\rightarrow 6I^{-}[/tex]

---------------------------------------------------------------------------------

Overall: [tex]2Al+3I_{2}\rightarrow 2Al^{3+}+6I^{-}[/tex]

Nernst equation for this cell reaction at [tex]25^{0}\textrm{C}[/tex]-

[tex]E_{cell}=E_{cell}^{0}-\frac{0.059}{n}log{[Al^{3+}]^{2}[I^{-}]^{6}}[/tex]

where n is number of electrons exchanged during cell reaction, [tex]E_{cell}^{0}[/tex] is standard cell emf , [tex]E_{cell}[/tex] is cell emf , [tex][Al^{3+}][/tex] is concentration of [tex]Al^{3+}[/tex] and [tex][Cl^{-}][/tex] is concentration of [tex]Cl^{-}[/tex]

Plug in all the given values in the above equation -

[tex]E_{cell}=2.20-\frac{0.059}{6}log[(4.5\times 10^{-3})^{2}\times (0.15)^{6}]V[/tex]

So, [tex]E_{cell}=2.32V[/tex]

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