1. Tardigrade
  2. Question
  3. Chemistry
  4. The emf of the following three cells I. Z n| Z n2+(1 M)|| C u2(1 M)| C u II. Z n| Z n2+(0.1 M)|| C u2(1 M)| C u III. Z n| Z n2+(1 M)|| C u2+(0.1 M)| C u are represented by E1, E2 and E3. Which of the following statement is correct?

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Q. The emf of the following three cells
I. $Z n\left| Z n^{2+}(1 M)\right|\left| C u^{2}(1\, M)\right| C u$
II. $Z n\left| Z n^{2+}(0.1 M)\right|\left| C u^{2}(1\, M)\right| C u$
III. $Z n\left| Z n^{2+}(1 M)\right|\left| C u^{2+}(0.1\, M)\right| C u$ are represented by $E_{1}, E_{2}$ and $E_{3}$.
Which of the following statement is correct?

AMUAMU 2015Electrochemistry

Solution:

$Z n +C u^{2+} \rightarrow Z n^{2+}+C u$ From Nernst equation,
$E_{\text {cell }}=E_{\text {cell }}^{o}-\frac{0.591}{n} \log \frac{[\text { Product }]}{[\text { Reactant }]}$
$E_{1}=-\frac{0.0591}{2} \log \frac{1\, M}{1\, M}=0$
$E_{2}=-\frac{0.0591}{2} \log \frac{0.1\, M}{1\, M}=+0.02955$
$E_{3}=-\frac{0.0591}{2} \log \frac{1\, M}{0.1\, M}=-0.0591$ Thus,
$E_{2}>E_{1}>E_{3}$