Question

Part a the disproportionation of mn2+(aq) to mn(s) and mno2(s) in acid solution at 25 ∘c. calculate δg∘rxn.

Answer 1

Answer:

Δ$G^{o}$ = -461198.3 J

Explanation:

Gibbs free energy is defined as the energy associated with a given chemical reaction which can be used to do work. Firstly, we need to figure out the chemical equation for the given problem. For the given problem, the chemical equation is:

$Mn^{2+} _{(aq)} + 2e^{-}$⇒$Mn_{(s)}$      $E^{o} = -1.18 V$

$Mn^{2+} _{(aq)} + H_{2}O$ ⇒$MnO_{2(s)} +4H^{+} + 2e^{-}$$E^{o} = -1.21 V$

The addition of the two $E^{o}$ gives the $E_{cell}$ of the equation, i.e. -1.18-1.21 = -2.39 V.

Then, using the equation for Δ$G^{o}$, we have:

Δ$G^{o}$ = n*F*$E^{o}$ = 2*96485*-2.39 = -461198.3 J