Balancing Redox Reaction by Half Reaction Method

[moouers]

Homework Statement

CuCl₂(aq)+Al(s)→AlCl₃(aq)+Cu(s)

Homework Equations

The Attempt at a Solution

I'm just not sure what to do with a situation involving compounds. I can do simple balancing without a problem. Here is my attempt. Please, please let me know where I went wrong...

Oxidation: Al→Al⁺³+3e^-
Reduction: Cu⁺²+2e^-→Cu
Reduction: 2Cl^-2→3Cl^-3 (?)

I'm confuzzled. I don't know where to go from here, or even if I did the above correctly. The book is pretty awful in describing these half-reaction equations, so I've been searching online but without any applicable results. I didn't think I should split the reduction into two parts, but maybe I do. I don't know. I also don't know what to do with the equation concerning the Chlorine. All around, I'm confused.

I can balance the equation just fine with the "trial and error" method, and it matches the back of the book, I just don't know how to get there by half-reactions.

Thank you so much for any help.

 

[Borek]

Cl^- is just a spectator and doesn't change during the reaction. Yes, you should split.

Check ChemBuddy page on the half reaction method. If it doesn't help, ask for clarification (here or there).

 

[moouers]

Well, gee. That was simple! Thank you very much, and thank you for the link. I suppose what got me then was my assumption that I understood spectator ions pretty well. I guess not! In this case, is Cl^- a spectator because we don't need to balance the charge since it stays the same throughout the reaction?

 

[Borek]

In this case, is Cl^- a spectator because we don't need to balance the charge since it stays the same throughout the reaction?

It is a spectator because it doesn't take part in the reaction. It doesn't take part in the reaction - so it doesn't change its charge.

 

[moouers]

Got it. Thanks.