Question

Which of the following redox reactions do you expect to occur spontaneously in the forward direction?

Check all that apply.

Cd2+(aq)+Co(s)→Co2+(aq)+Cd(s)

Pb(s)+Mn2+(aq)→Pb2+(aq)+Mn(s)

Al(s)+3Ag+(aq)→Al3+(aq)+3Ag(s)

Ni(s)+Pb2+(aq)→Ni2+(aq)+Pb(s)

Answer 1

part1)

from data table:

Eo(Co2+/Co(s)) = -0.28

Eo(Cd2+/Cd(s)) = -0.4

The chemical reaction taking place is

Cd2+(aq) + Co(s) --> Cd(s) + Co2+(aq)

Eocell = Eocathode - Eoanode

= (-0.4) - (-0.28)

= -0.12 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is negative

So, This reaction is not spontaneous

part2)

from data table:

Eo(Pb2+/Pb(s)) = -0.126

Eo(Mn2+/Mn(s)) = -1.185

The chemical reaction taking place is

Mn2+(aq) + Pb(s) --> Mn(s) + Pb2+(aq)

Eocell = Eocathode - Eoanode

= (-1.185) - (-0.126)

= -1.059 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is negative

So, This reaction is not spontaneous

part3)

from data table:

Eo(Al3+/Al(s)) = -1.662

Eo(Ag+/Ag(s)) = 0.8

The chemical reaction taking place is

Ag+(aq) + Al(s) --> Ag(s) + Al3+(aq)

Eocell = Eocathode - Eoanode

= (0.8) - (-1.662)

= 2.462 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is positive

So, This reaction is spontaneous

part4)

from data table:

Eo(Ni2+/Ni(s)) = -0.25

Eo(Pb2+/Pb(s)) = -0.126

The chemical reaction taking place is

Pb2+(aq) + Ni(s) --> Pb(s) + Ni2+(aq)

Eocell = Eocathode - Eoanode

= (-0.126) - (-0.25)

= 0.124 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is positive

So, This reaction is spontaneous

Last 2 reactions are spontaneous

Answer:

Al(s)+3Ag+(aq)→Al3+(aq)+3Ag(s)

Ni(s)+Pb2+(aq)→Ni2+(aq)+Pb(s)