The ions of which element will not oxidize cobalt?

Question

a. Sn

b. Cr

c. Cu

d. Hg

e. none of the above

Answer 1

From a table of standard reduction potentials, Cr³⁺, Cu²⁺ and Hg²⁺ all have greater reduction potentials that Co²⁺ so they would act to oxidize the cobalt.