Question

Consider a voltaic cell based on the following cell reaction:
Ni(s) + At2(s) —> Ni2+(aq) + 2At– (aq)

Given that the standard cell emf is 0.55 V, what is the standard reduction potential for astatine? [Ecell(Ni2+/Ni) = –0.25 V]

Answer 1

To find the standard reduction potential for astatine (At), we can use the formula:

Ecell = Ereduction (cathode) - Eoxidation (anode)

where Ecell is the standard cell emf, Ereduction is the standard reduction potential for the cathode (Ni2+/Ni), and Eoxidation is the standard oxidation potential for the anode (At/At-).

We are given that Ecell = 0.55 V and Ereduction (Ni2+/Ni) = -0.25 V. We can rearrange the formula to solve for Eoxidation:

Eoxidation (At/At-) = Ereduction (cathode) - Ecell

Eoxidation (At/At-) = -0.25 V - 0.55 V

Eoxidation (At/At-) = -0.80 V

Therefore, the standard oxidation potential for astatine is -0.80 V, which is also the standard reduction potential for astatine since the reaction is reversible.