Question

Consider the following half-reactions:

Half-reaction	E° (V)
Hg2+(aq) + 2e- ----> Hg(l)	0.855V
Cd2+(aq) + 2e- --->Cd(s)	-0.403V
Mg2+(aq) + 2e- --->Mg(s)	-2.370V

(1) The strongest oxidizing agent is:

enter formula

(2) The weakest oxidizing agent is:

(3) The weakest reducing agent is:

(4) The strongest reducing agent is:

(5) Will Mg²⁺(aq) oxidize Hg(l) to Hg²⁺(aq)? _____yes/no

(6) Which species can be reduced by Cd(s)? If none, leave box blank.

Answer 1

(1) The strongest oxidizing agent is Hg²⁺. It has the largest standard electrode potential and thus easiest to reduce.

(2) The weakest oxidizing agent is Mg²⁺, because it has the smallest standard electrode potential.

(3) The weakest reducing agent is Hg(l) as it is most difficult to oxidize. Hg(l) is the reduced form of strongest oxidizing agent, Hg²⁺.

(4) The strongest reducing agent is Mg(s) as it is easiest to oxidize. Mg(s) is the reduced form of the weakest oxidizing agent, Mg²⁺.

(5) Mg²⁺ is weakest oxidizing agent. Hence, it cannot oxidize Hg(l).

(6) In order for a species to be reduced by Cd(s), it should have a larger standard reduction potential than Cd. Thus, Hg²⁺ can be reduced by Cd(s).