Chapter 19, Problem 19.103SP

At one time on Earth, iron was present mostly as iron(II). Later, once plants had produced a significant quantity of oxygen in the atmosphere, the iron became oxidized to iron(II1). Show that $F{e}^{2+}(aq)$ can he spontaneously oxidized to $F{e}^{3+}(aq)$ by $O_2(g)$ at 25^o C assuming the following reasonable environmental conditions:
${\text{[Fe}}^{\text{2+}}{\text{]=[Fe}}^{\text{3+}}{\text{]=1×10}}^{\text{-7}}\text{M;pH=7}{\text{.0;Po}}_{\text{2}}\text{=160mm Hg}\text{.}$