Ligands and balancing?

[meganba]

I'm feeling pretty stumped on this one,if anyone has any suggestions it would be mucho apreciado:

So, we start out with a cobalt complex [Co(H₂O)₆}Cl₂, + H₂O₂ + NH₃ + HCL to try and form =>[Co(NH₃)₅ Cl]Cl₂ + H₂₀ + somesort of Cl ion (this is what my teacher suggested, I don't really get that part).

I've been trying to balance this baby forever,and the closest I can come is identifying that there was a redox reaction with the Co andd the H₂O₂ that went something like:
2Co²⁺ + 2H₂O₂ = 2Co³⁺ +H₂O +2OH^-

Does anyone have any suggestions on how to balance the Co complex to get [Co(NH₃)₅ Cl]Cl₂ from [Co(H₂O)₆}Cl₂?


Thank you!

-a very lost Megan

[Zedekiah]

It looks like you're on the right track with the hydrogen peroxide oxidizing the cobalt. The HCl in the reaction hints that you're going to have to balance its reduction in acidic conditions, however.

Code: Select all

2e- + 2H+ + H2O2        -------->       2H2O
2Co2+       -------->      2Co3+ + 2e-

The overall reaction may read something like this :

Code: Select all

10NH3 + 2[Co(H2O)6]Cl2 + H2O2 + 2HCl       ------->           2[Co(NH3)5Cl]Cl2 + 14H2O

I'm not sure what to think about a Cl containing product; if you have enough peroxide in solution to make

Code: Select all

Cl2

it is enough to precipitate the cobalt.

Hope that helps!