Question

A student was given a standard fe(s)| fe2+(aq) half-cell and another halfcell containing an unknown metal, m(s), immersed in 1 m mno3(aq). when these two half-cells were connected at 25◦c, the complete cell functioned as a galvanic cell with e = 1.24 v. the reaction was allowed to proceed for a short amount of time and the two electrodes were weighed. the iron electrode was found to be lighter than its initial mass and the unknown metal electrode was heavier than its initial mass. what is the standard potential of the unknown m+/m couple? 1. +2.04 v 2. −0.36 v 3. +1.68 v

Answer 1

Hey there!:

From the given information , we conculde that the in the given cell .

* Fe (s) is oxidized and M⁺² ion is reduced, hence

* The cell reaction would be:

Fe(s) + M⁺² (aq) ---------> M (s) + Fe⁺²(aq)

* all are in 1.0 M concentrations

*Hence we conclude this cell is at the standard conditions.

Thus :

Eo(cell) = Eo(cathode) + Eo (anode)

from the standard data : Fe⁺² / Fe = -0.41 V

Therefore :

1.24 V = Eo(cathode) + 0.41 V

Eo(cathode) = 1.24 -0.41

Eo(cathode)  = + 0.83 V

Hope that helps!