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...
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?
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.
Your reasoning for the ordering of the metal-metal ion reactions is not entirely correct. The ability of a metal to act as an oxidizing agent (i.e., to gain electrons and be reduced) depends on its tendency to attract and accept electrons. The higher the tendency to attract electrons, the stronger the oxidizing agent it is.
To determine the ordering correctly, you need to consider the standard reduction potentials (E°) of the metal-metal ion reactions. The lower the reduction potential value, the stronger the oxidizing agent.
Here are the standard reduction potentials for the reactions you listed:
1) Cu2+ + 2e^- --> Cu E° = 0.34 V
2) Ni2+ + 2e^- --> Ni E° = -0.25 V
3) Al3+ + 3e^- --> Al E° = -1.66 V
Based on these values, we can see that Al3+ has the most negative reduction potential, making it the strongest oxidizing agent. Therefore, it should be at the top of the column.
The next in line is Cu2+, which has a less negative reduction potential than Al3+. Lastly, Ni2+ has the least negative reduction potential, making it the weakest oxidizing agent.
So, the correct ordering of the metal-metal ion reactions in terms of decreasing ability as oxidizing agents would be:
1) Al3+ + 3e^- --> Al
2) Cu2+ + 2e^- --> Cu
3) Ni2+ + 2e^- --> Ni