Question

If E°Fe2+/Fe is X1 , E°Fe3+/Fe is x2 ; then E°Fe+3/Fe+2 will be
(1) 3x2 - 2x1
(2)x2 - x1
(3) x2 + x1
(4)2x1 + 3x2

Answer 1

Answer : The correct option is, (1) $3X_2-2X_1$

Explanation :

$E^0_{[Fe^{2+}/Fe]}=X_1$

$E^0_{[Fe^{3+}/Fe]}=X_2$

$\Delta G^o$ for $E^0_{[Fe^{2+}/Fe]}=X_1$

The half reaction will be,

$Fe^{2+}+2e^-\rightarrow Fe$

$\Delta G^o_1=-2F\times X_1$     .......(1)

$\Delta G^o$ for $E^0_{[Fe^{3+}/Fe]}=X_2$

The half reaction will be,

$Fe^{3+}+3e^-\rightarrow Fe$

$\Delta G^o_2=-3F\times X_2$    .....(2)

Now we have to determine the $\Delta G^o$ for $E^0_{[Fe^{3+}/Fe^{2+}]}$

The half reaction will be,

$Fe^{3+}+e^-\rightarrow Fe^{2+}$       ......(3)

$\Delta G^o=-1F\times E^0_{[Fe^{3+}/Fe^{2+}]}$

Now reverse the equation 1 and add with equation 2, we get the equation 3.

$\Delta G^o=\Delta G^o_1+\Delta G^o_2$

$-1F\times E^0_{[Fe^{3+}/Fe^{2+}]}=2F\times X_1+(-3F\times X_2)$

$E^0_{[Fe^{3+}/Fe^{2+}]}=3X_2-2X_1$

Therefore, the correct option is, (1) $3X_2-2X_1$

Answer 2

Explanation:

hope this will help you