An excess of liquid mercury is added to an acidified solution of 1.0 $$\times$$ 10^-3 M Fe³⁺. It is found that 5% of Fe³⁺ remains at equilibrium at 25^oC. Calculate $$E_{Hg_2^{2 + }|\,Hg}^o$$, assuming that only reaction that occurs is
2Hg + 2Fe³⁺ $$\to$$ $$Hg_2^{2+}$$ + 2Fe²⁺
(Given $$E_{F{e^{3 + }}|\,F{e^{2 + }}}^o$$ = 0.77 V)

The Edison storage cells is represented as
Fe(s) | FeO(s) | KOH (aq) | Ni₂O₃(s) | Ni(s)
The half-cell reactions are:
Ni₂O₃ + H₂O (l) + 2e^- $$\leftrightharpoons$$ 2NiO(s) + 2OH^-; E^o = +0.40V
FeO(s) + H₂O(l) + 2e^- $$\leftrightharpoons$$ Fe(s) + 2OH^-; E^o = -0.87V
(i) What is the cell reaction?
(ii) What is the cell e.m.f? How does it depend on the concentration of KOH?
(iii) What is the maximum amount of electrical energy that can be obtained from one mole of Ni₂O₃?

The standard reduction potential of the Ag⁺/Ag electrode at 298 K is 0.799V. Given that for AgI, K_sp = 8.7 $$\times$$ 10^-17, evaluate the potential of the Ag⁺/Ag electrode in a saturated solution of AgI. Also calculate the standard reduction potential of the I^-/ AgI/Ag electrode.

The standard reduction potential for the half-cell
$$NO_3^-$$ + 2H⁺ (aq) + e $$\to$$ NO₂ (g) + H₂O is 0.78 V
(i) Calculate the reduction potential in 8 M H⁺
(ii) What will be the reduction potential of the half-cell in a neutral solution? Assume all the other species to be at unit concentration.