Question

The emf of the cell $\text{Ni/N}{\text{i}}^{+2}\left(1.0\text{M}\right)\parallel \text{A}{\text{u}}^{\text{+ 3}}\left(\text{0}\text{.1M}\right)\text{/Au}$ $\left[{\text{E}}^{\circ }\text{for}\text{N}{\text{i}}^{\text{+ 2}}\text{/Ni}=-0.25\text{V},{\text{E}}^{\circ }\text{for}\text{A}{\text{u}}^{+3}/\text{Au}=1.50\text{V}\right]$
is given as:

• A. $1.25V$
• B. $-1.75V$
• C. $1.75V$
• D. $1.73V$

Answer 1

The correct option is D $1.73V$

$3Ni+2A{u}^{3+}⟶3N{i}^{2+}+2Au$

Nernst equation,

$E_{cell}=E^o-\frac{0.059}{n}\log \left[\frac{(N{i}^{2+}{)}^3}{(A{u}^{3+}{)}^2}\right]$

$E_{cell}=(1.50-(-0.25\left)\right)-\frac{0.059}{6}\log \left[100\right]$

$E_{cell}=1.75-0.02$

$E_{cell}=1.73$ $V$