Question

What reactions take place at the cathode and the anode when each of the following is electrolyzed? (Use the lowest possible coefficients. Omit states of matter. If a box is not needed, leave it blank.)

a. molten CoBr_2
At the cathode:____________
At the anode:__________

Answer 1

When molten CoBr2 is electrolyzed, cobalt ions are reduced to metallic cobalt at the cathode, and bromide ions are oxidized to bromine gas at the anode. These reactions result in the direct consumption or production of ions.

Step-by-step explanation:

When molten CoBr2 is electrolyzed, different reactions occur at the cathode and anode due to the external electric current passing through the molten salt. At the cathode, the reduction of cobalt ions to metallic cobalt takes place:

At the cathode: Co2+ + 2e- → Co

At the anode, bromide ions are oxidized to bromine gas:

At the anode: 2Br- - 2e- → Br2

It's important to remember that the electrode potentials for molten salts are likely to be quite different from those in aqueous solution, and the electrolysis of molten salts operates based on the direct production or consumption of ions present in the electrolyte, without water participating in the electrochemical reactions.

Answer 2

During the electrolysis of molten CoBr2, Co2+ ions are reduced to Co metal at the cathode, while bromide ions are oxidized to bromine at the anode.

Step-by-step explanation:

When molten CoBr2 is electrolyzed, at the cathode, Co2+ ions are reduced to Co metal:

2Co2+(l) + 2e- -> 2Co(s)

At the anode, Bromide ions (Br-) are oxidized to Bromine (Br2):

2Br-(l) -> Br2(g) + 2e-