Question

For the following electron-transfer reaction:Co(s) + 2Ag+(aq) Co2+(aq) + 2Ag(s)Find the oxidation half-reaction & the reduction half-reaction

Answer 1

We have the chemical equation:

$Co+2Ag^+\to Co^{2+}_{}+2\text{ Ag}.$

You can realize that the cobalt (Co) in the reactant doesn't have any charge, but in the product is losing two electrons (it is a cation), this means that is oxidating. The oxidation half-reaction is:

$Co\to Co^{2+}+e^-.$

And the Ag (silver), is gaining one electron, because in the reactants loses one electron per 2 moles of Ag. The reduction half-reaction is:

$2Ag^++e^-\to\text{ 2Ag.}$