Question

Give: E⁰_{Mn⁺⁷|Mn⁺²} = 1.5 V and E⁰_{Mn⁺⁴|Mn⁺²} = 1.2 V, then E⁰_{Mn⁺⁷|Mn⁺⁴} is

• A. 1.7 V
• B. 2.1 V
• C. 0.3 V
• D. 0.1 V

Answer 1

Answer: (A)

$M{n}^{+7}+5e^{-}\to M{n}^{2+}$
$M{n}^{+4}+2e^{-}\to M{n}^{2+}$
$Requiredequation$
$M{n}^{+7}+3e^{-}\to M{n}^{4+}$
$\therefore -3F{E}^{º-}=-7.5F+2.4F$
$\therefore E^{º-}=1.7V$
$\Delta G^{º-}=-5F1.5,$
$\Delta G^{º-}=-2F1.2,$
$\Delta G^{º-}=-3F{E}^{º-}$