∵Fe3++3e−→Fe;E∘=−0.036 V∴ΔG1∘=−nFE∘=−3 F(−0.036)=+0.108 F Also Fe2++2e−→Fe;E∘=−0.439 V∴ΔG2∘=−nFE∘=−2 F(−0.439)=0.878 F To find E∘ for Fe(aq)3++e−→Fe2+(aq)ΔG∘=−nFE∘=−1FE∘∵G∘=G1∘−G2∘∴G∘=0.108 F−0.878 F∴−FE∘=+0.108 F−0.878 F∴E∘=0.878−0.108=0.77 V