Question

Examine the following half-reactions and select the strongest oxidizing agent among the species listed.

Cr 2+(aq) + 2e- = Cr (s) E= -0.913 V
Fe 2+(aq) + 2e- = Fe (s) E= -0.447 V
Sr 2+(aq) + 2e- = Sr (s) E= -2.89 V
Co 2+(aq) + 2e- = Co (s) E= -0.28 V

a. Co 2+(aq)
b. Fe (s)
c. Fe 2+ (aq)
d. Sr 2+ (aq)
e. Cr 2+ (aq)

Answer 1

Answer:

a. Co²⁺(aq)

Explanation:

The standard potential in a redox reaction (E) allows  the classification of different substances according to their oxidizing and reducing power.

For the reactions:

Cr²⁺(aq) + 2e⁻ = Cr(s) E= -0.913 V

Fe²⁺(aq) + 2e⁻ = Fe(s) E= -0.447 V

Sr²⁺(aq) + 2e⁻ = Sr(s) E= -2.89 V

Co²⁺(aq) + 2e⁻ = Co(s) E= -0.28 V

If the standard potential for the reaction is positive, the reaction will occur spontaneously. As these reactions are of reductions, the more positive E will be the strongest oxidizing agent. For that reason the right answer is:

a. Co²⁺(aq)

I hope it helps!