Additional data needed for this question can be found in Appendix 11.

(a) Determine E_Zn²⁺/Zn (at 298 K) for a half-cell in which [Zn²⁺] = 0.25 mol dm⁻³.

(b) Calculate the reduction potential for the half reaction:

if the ratio of the concentrations of [VO]²⁺: V³⁺ is 1 :2 and the pH of the solution is 2.2.

Data from Appendix 11

The concentration of each aqueous solution is 1 mol dm⁻³ and the pressure of a gaseous component is 1 bar (10⁵ Pa). (Changing the standard pressure to 1 atm (101 300 Pa) makes no difference to the values of E^o at this level of accuracy.) Each half-cell listed contains the specified solution species at a concentration of 1 mol dm⁻³; where the half-cell contains [OH]⁻, the value of E^o refers to [OH⁻] = 1 mol dm⁻³, hence the notation E^o_{[OH⁻] = 1}

[VO]+ (aq) + 2H+ (aq) +e=V+ (aq) + HO(1)