Question

A voltaic cell is constructed based on the following reaction and initial concentrations: Fe2+( F e 2 + ( 0.0045 M)+Ag+( ) + A g + ( 2.3 M M )⇌ ) ⇌ Fe3+( F e 3 + ( 0.0045 M M )+Ag(s)

-Calculate [Fe2+]when the cell reaction reaches equilibrium.

Answer 1

Solution :

Reaction is :

Fe2+ + Ag+ ---> Fe3+ + Ag(s)

Initial Conc. 0.0045 M 2.3 M 0.0045     

Equili. Con. (0.0045 - x) (2.3-x) (0.0045 + x)

Now Equilibrium Conc. of this reaction is :

Keq = 3.218

Conc. of Products/Conc. of Reactants = 3.218

(0.0045 + x) / ((0.0045 - x) * (2.3-x)) = 3.218

(0.0045 + x) = 7.4 * (0.0045 - x)

So, x = 3.4293 * 10-3 M

• [Fe2+]when the cell reaction reaches equilibrium = (0.0045 - x)

= (0.0045 - 3.4293 * 10-3 )

= 1.071 * 10-3 M