Question

Determine whether the following redox reactions are spontaneous as written? (Use the information in the table below. Show the half reactions and the potentials for each half reaction.)
a. 2Ag(s) + Mg2+(aq) → 2Ag+ (aq) + Mg(s) [5 points]

b. 2Al(s) + 3Zn2+(aq) → 2Al3+(aq) + 3Zn(s) [5 points]

Reduction Potentials at 25°C
Electrode Half-Reaction E0(V)
Mg2+/Mg Mg2+ + 2e– → Mg –2.37
Al3+/Al Al3+ + 3e– → Al –1.66
Zn2+/Zn Zn2+ + 2e– → Zn –0.76
Ag2+/Ag Ag+ + e– → Ag +0.80

Answer 1

2Ag(s) + Mg2+(aq) → 2Ag+ (aq) + Mg(s) [5 points]
2Ag(s) ==>2 Ag^+ + e ...........E = -0.80
Mg^2+ + 2e ==> Mg(s) ......E = -2.87
--------------------------------------------
2Ag(s) + Mg^2+ ==> 2Ag^+ +Mg(s) E = -3.67
E cell is negative. It will not be spontaneous.
The others are done the same way.