Standard potential

Question

A galvanic cell consists of an inert platinum electrode in a solution containing 1.0 M chromium(II) ion and 1.0 M chromium(II) ion, and another inert platinum electrode in a solution containing 1.0M cerium (III) ion, connected by a salt bridge. Calculate the standard potential for this cell at 25 Celsius.

Answer 1

In order to address this problem, we must consult a table of standard reduction potentials. Assuming that one half cell is 1.0 M chromium (III) and 1.0 M chromium (II) and not as written where both ions are chromium(II)..

The table gives the following:

Cr³⁺ + e- ==> Cr²⁺ ... Eº = -0.407 V

Ce³⁺ + 3e- ==> Ce ... Eº = -2.34 V

Accordingly, Cr³⁺/Pt will act as the cathode and Ce³⁺/Pt will act as the anode

Eº_cell = -0.407 V + 2.34 V = 1.93 V