Half reaction E0,(v)
Ni2+(aq) + 2e- Ni(s) -0.23
Co2+(aq) + 2e- Co(s) -0.28
Fe2+(aq) + 2e- Fe(s) -0.41
Cr3+(aq) + 3e- Cr(s) -0.74
Mn2+(aq) + 2e- Mn(s) -1.03
Which of the following metals could be used successfully to galvanize steel?
Zn forms a series of layers of alloys with iron and lowers the oxidation rate of iron by a factor of 10 to 100. At least one reason for the protective powers of Zn is because Zn serves as a sacrificial anode; i.e., it is easier to oxidize Zn metal than Fe metal. The potential for Zn^2+ + 2e ==> Zn is -0.763 and Fe^2+ + 2e ==> Fe is about -0.40. Therefore, you want a reduction potential more negative than -0.040. Thus I would go with Mn or Cr assuming that they would form a coating that will cling to the iron base metal.
To determine which of the given metals can be used successfully to galvanize steel, we need to compare their standard reduction potentials (E0).
The more negative the reduction potential, the better the metal can act as a reducing agent and protect the steel from oxidation.
In this case, we are looking for a metal that has a more negative reduction potential than iron (Fe) since we want it to protect the steel. The reduction potential of Fe is -0.41 V.
Therefore, any metal with a more negative reduction potential than -0.41 V can be used successfully to galvanize steel.
From the given half-reactions and their reduction potentials, we can see that nickel (Ni) has a reduction potential of -0.23 V, cobalt (Co) has a reduction potential of -0.28 V, and chromium (Cr) has a reduction potential of -0.74 V.
Both nickel and cobalt have more negative reduction potentials than iron, so they can be used successfully to galvanize steel. Chromium, however, does not have a more negative reduction potential than iron, so it may not be suitable for galvanizing steel.
Therefore, nickel and cobalt could be used successfully to galvanize steel.