Question

An electrochemical cell is based on the following two half-reactions:
Ox: Sn(s)→Sn2+(aq, 1.50 M )+2e−
Red: ClO2(g, 0.150 atm )+e−→ClO−2(aq, 1.50 M )

Compute the cell potential at 25 ∘C .

Answer 1

Nernest equation,

Sn2+ + 2 e− ⇌ Sn(s)    E0 = −0.13 V   

ClO2(g) + H+ + e− ⇌ HClO2(aq) E0 = +1.19 v

cell reaction = Sn(s) + 2ClO2(g) ----> Sn2+(aq) + 2ClO2^-(aq)

E0cell = E0cathode - E0anode

         = 1.19 - (-0.13)

         = 1.32 v

   Ecell = E0cell - 0.0591/nlog[[clo2-]^2[sn2+]/[clo2]^2]

         = 1.32-(0.0591/2)log ((1.5*1.5^2)/0.15^2)

         = 1.256 v