Question

For a relation:

Δ_rG = −nFE_cell

\[\ce{E_{cell} = E^\circ_{cell}}\] in which of the following conditions?

Options

• The concentration of any one of the reacting species should be unity.

• The concentration of all the product species should be unity.

• The concentration of all the reacting species should be unity.

• The concentration of all reacting and product species should be unity.

Answer 1

The concentration of all reacting and product species should be unity.

Explanation:

When the concentration of all reacting and product species is kept at unity, then \[\ce{E_{cell} = E^\circ_{cell}}\] and the given relation will become `Δ_rG = -nFE_(cell)^\circ`.

E.g., redox reaction for a Daniell cell:

\[\ce{Zn_{(s)} + Cu^{2+}_{ (aq)} -> Zn^{2+}_{ (aq)} + Cu_{(s)}}\]

Solutions of CuSO₄ and ZnSO₄ are the reacting species.

The E_cell for this cell: \[\ce{E_{cell} = E^\circ_{cell}}\]

`-(RT)/(nF) ln  ([Zn^(2+)])/([Cu^(2+)])`

E_cell = E_cell

if [Zn²⁺] = [Cu²⁺] = 1