Reduction potentials for half-cell reactions of simple carbon species measured in aqueous solution at pH 7.0, 25°C, are as follows.

(a) Assign carbon oxidation numbers to each of the species involved.

(b) Construct a Frost diagram, making HCHO the reference point at the origin.

(c) Identify the redox couple having the most positive reduction potential.

(d) Is hydration of CO to give formate (HCO₂⁻) favourable at pH 7.0?

(e) At pH 7.0, 25°C, the reduction potential for the hydrogen half-cell is given by:

Calculate the equilibrium constant for the water-gas shift reaction

in aqueous solution, under these conditions.

Transcribed Image Text:

CO₂(g) + 4H+ + 4e →HCHO(aq) + H₂O E = -0.51V CO,(g)+e → COz(aq) E = -1.90 V CO₂(g) + 2H+ + 2e → CO(g) + H₂O E = -0.52 V CO₂(g) + H+ + 2e → HCO₂(aq) E = -0.43 V