Question

Free Energy

(a) Which type of electrochemical cell has ?Gsys < 0 ?

(b) Which type shows an increase in free energy ?

(c) What is the value for the Keq and ?G° for the reaction between each pair:

(i) Ni(s) and Ag+(aq)

(ii) Fe(s) and Cr3+(aq)

(d) What are E°cell and ?G° of a redox reaction at 25°C for which n=1 and K = 5.0 × 104 ?

Answer 1

a) galvanic cell

b)electrolytic cell

c) i) K=6.27x10'34

ΔG°=198790 J

ii) K=3.58x10'-34

ΔG°= 191070 J

d) E°=0.278 v

ΔG°= -26827 J

Step-by-step explanation:

a) There are two kinds of an electrochemical cell, the first is called "galvanic cells", and the second "electrolytic cell".

The fuel cells are capable of produce electric energy through chemical reactions. These reactions are often spontaneous. So, the galvanic cell has a negative value for Gibbs free energy.

b) The electrolytic cell increases the value of Gibbs energy, to positive values, due to the reactions are not spontaneous.

c) i) look image attached

ii) k = look image attached

ΔG° = -nFE° = - 6 X 95500 J/vmole x (-0.33 v)

ΔG° =-191070

d) E°= 0.0592 v/n x lg K

E°= 0.0592V / 1 X log 5.0X10'4

E°= 0.278 v

ΔG° = -nFE° = -1 x 96500 J/ vmole x 0.278v

ΔG° = -26827 J