The standard reduction potential ( E^ ) of the F₂/F^- electrode is the highest among all halogens, making F₂ the most powerful oxidizing agent. Which of the following thermodynamic factors primarily account for this exceptionally high E^ value? (I) Highly negative hydration enthalpy of the F^- ion. (II) Lower bond dissociation enthalpy of the F₂ molecule compared to Cl₂ . (III) More negative electron gain enthalpy of

Step-by-step solution

The standard reduction potential ( E^ ) of a halogen is determined by the overall enthalpy change of the following three steps: 1. Dissociation of the halogen molecule into atoms: 1 2 X₂(g) X(g) (Bond dissociation enthalpy, _ diss H^ ) 2. Addition of an electron to the atom: X(g) + e^- X^-(g) (Electron gain enthalpy, _ eg H^ ) 3. Hydration of the gaseous ion: X^-(g) + aq X^-(aq) (Hydration enthalpy, _ hyd H^ ) For fluorine, the bond dissociation enthalpy of F₂ is lower than that of Cl₂ due to strong interelectronic