Question

The standard oxidation potential of `Ni//Ni^(2+)` electrode is `0.236 V`. If this is combined with a hydrogen electrode in acid solution, at what `pH` of this solution will be measured e.m.f. be zero at `25^(@)C`? Assume that `[Ni^(2+)] = 1 M` and `P_(H_(2)) = 1 atm`.

Answer 1

Correct Answer - 4
`{:(NitoNi^(+)+2e,,E_(OP)^(@)=0.236 V),(2H^(+)+2etoH_(2),,E_(RP)^(@)=0),(,bar(E_("cell")^(@)=0.236 V)):}`
`E_(cell) = E_(cell)^(@) +(0.059)/(2)"log"_(10)([H^(+)]^(2))/([Ni^(2+)])`
`0 = 0.236 + (0.059)/(2)"log"_(10)[H^(+)]^(2)`
`log_(10)H^(+) = 4 :. pH = 4`