# Can carbon dioxide be used as oxidant for iron?

Determine whether it is possible for $$\ce{CO2}$$ to be an oxidant for $$\ce{Fe}$$. Justify your choice by comparing the corresponding half reactions.

I found the following half-reactions, both on reduction form:

\begin{align} \tag{I}\label{I} \ce{Fe^2+ + 2e^- &<=> Fe(s)} & E^\circ &= \pu{-0.44 V}\\ \tag{II}\label{II} \ce{CO2(g) + 2H^+ + 2e^- &<<=> CO(g) + H2O}& E^\circ &= \pu{-0.1 V} \end{align}

As iron should be oxidized, we turn \eqref{I} the other way and change the sign:

\begin{align} \ce{Fe(s) &<=> Fe^2+ + 2e^-}& E^\circ &= \pu{0.44V}\\ &&E^\circ(\text{total}) &= \pu{0.44 V} - \pu{0.1 V} = \pu{0.34V} \end{align}

$$E^\circ(\text{total}) > 0$$, and the reaction is spontaneous. But according to the solution manual $$E^\circ(\text{total})$$ should be less than $$0$$. Have I misinterpreted the task?

• @HarshWasnik We prefer to not use MathJax in the title field, see here for details. – Martin - マーチン May 19 at 11:30
• Anyone able to help me ? – Kdbmvp May 20 at 12:17