1) Arrange the metal-metal ion reactions (aluminum, copper, nickel), M^n+ + ne^- --> M^0, in a column, in order of decreasing ability as oxidizing agents...

Question

What I put was :
Al^+3 + 3e^- --->Al
Ni^+2 + 2e^- --->Ni
Cu^+2 + 2e^- --->Cu

2) Also, explain your reasoning for the ordering shown above.

My reason was because the metal that reacts with both other metals belongs at the top while the metal that doesn't react with any of the two belongs at the bottom.

Is this correct?

Answer 1

A metal acts as oxidizing agent as it gets reduced by taking electrons away from another metal. Example:

Cu^+2(aq) + Ni --> Cu(s) + Ni^+2(aq)
Cu(s) + Ni^+2(aq) --> No Reaction

You are comparing the activity of these metals in their ionic form. Which is more active, Ni^+2, or Cu^+2 in reacting with another metal in pure form? Now you decide if your order is correct or should be reversed.