Ascorbic acid (Asc: Vitamin C) is a monoanion at neutral pH. It is a powerful antioxidant, which scavenges free radicals. It is oxidized in a single-electron oxidation to the monodehydroascorbate radical anion (MDHA-) according to the reaction Asc^- rightarrow MDHA^- + H^+ + e^-. The half-reaction has a standard reduction potential epsilon degree' of +0.330 V. Ascorbate also undergoes a two-electron oxidation to dehydroascorbate (DHA): Asc^- rightarrow DHA + H^+ + 2e^- This half-reaction has a standard reduction potential epsilon degree '' of +0.08 V. Finally, MDHA^-- undergoes a disproportionation reaction: 2 MDHA^- + H^+ rightarrow DHA + Asc^- Determine the biochemical standard free-energy change Delta G degree' for this reaction.