$E^o _{Cr^{3+} / Cr} = - 0.72\, V, \,$ અને $E^o _{Fe^{2+} / Fe} =-0.42 \,V$ હોય તો નીચેના કોષનો પોટેન્શિયલ .............. $V$.

$Cr\, | \,Cr^{3+}_{(0.1\,M)}\,||\, Fe^{2+}_{(0.01\, M)}\,|\, Fe$

Question

$E^o _{Cr^{3+} / Cr} = - 0.72\, V, \,$ અને $E^o _{Fe^{2+} / Fe} =-0.42 \,V$ હોય તો નીચેના કોષનો પોટેન્શિયલ .............. $V$.

$Cr\, | \,Cr^{3+}_{(0.1\,M)}\,||\, Fe^{2+}_{(0.01\, M)}\,|\, Fe$

AIEEE 2008, Diffcult

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Solution

d
$E_{c e l l}=E_{F e^{2+} / F e}^{0}-E_{C r^{3}+/ C r}^{\circ}-$$\frac{0.059}{6} \log \frac{\left[C r^{3+}\right]^{2}}{\left[F e^{2 t}\right]^{3}}$

$=-0.42-(-0.72)-\frac{0.059}{6} \log \frac{(0.1)^{2}}{(0.01)^{3}}$

$=-0.42+0.72-\frac{0.059}{6} \log \frac{0.1 \times 0.1}{0.01 \times 0.01 \times 0.01}$

$=0.3-\frac{0.059}{6} \log \frac{10^{-2}}{10^{-6}}$

$=0.3-\frac{0.059}{6} \times 4$

$=0.30-0.0393=0.26 V$

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