3.5    Write the Nernst equation and emf of the following cells at 298 K:

            (iii)Sn(s)|Sn^{2+}(0.050M)||H^{+}(0.020M)|H_{2}(g)(1 bar)Pt(s)

Answers (1)

The nernst equation for this reaction gives :- 

                                    E_{Cell} = E_{cell}^{\circ}\ - \frac{0.0591}{n}log \frac{[Sn^{+2}]}{\left [ H^+ \right ]^2}

Now for emf, just put all the values.

                                    E_{Cell} =0 - (-0.14) - \frac{0.0591}{2}log \frac{0.050}{0.020^2}

or                                             = 0.14 - 0.0295 \times log125

or                                             = 0.14 - 0.062 = 0.078\ V

Thus emf of the cell is 0.078 V.

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