Oxidation Number

[haley f]

I'm having some trouble with this Sapling problem. I know that Cl2 has a charge of 2- so the coordination compound must have a charge of 2+, so would the charge of Co be 3+?
Give the oxidation state of the metal species in the complex [Co(NH3)5Cl]Cl2

[Mahnoor_Wani_1I]

Yes, you are correct. +3 is the oxidation state of the Co. NH3 is neutral and since the charge of two chlorine outside is -2 the compound charge must be +2. Therefore, since Cl inside has a charge of -1 you set this equation: X -1 = +2. The X aka the oxidation of Co is +3

[Joseph Hsing 2C]

Yes you're correct for accounting for both the ligands inside and outside of the coordination sphere.

[Victoria Dao 3G]

Yes you are exactly correct. I think a good way to think about it is just to remember that the overall charge of the cation and anion should equal zero. You can do:
X + (0)(NH3) + (-1) + 2(-1) = 0
where x is the unknown oxidation number for cobalt, NH3 is a neutral atom, and chlorine (a halogen) is known to have a -1 oxidation number. This would apply to any other ligand and complex ion problem too! Hope this helps.

[Lesly Lopez 3A]

Hi!

Correct, you are right. From my understanding, NH3 is neutral therefore the charge of two chlorine outside would be -2. The compound charge must then be +2 for everything to make sense. That is why, in this case, Cl has a charge of -1 you set this equation: X -1 = +2. It may sound confusing but once you get it, it will make a lot more sense promise.

[Sharon Kim 2A]

An easy way for me to find the oxidation number is to find the anion charge first and determine what the overall charge of the coordinate compound is. Whether it is 0 or -2, -1, etc. Using that to find the oxidation number so that the charges in the compound matches the overall charge.

[CesarLec1]

Try treating the atoms inside the molecule as one entire molecule to better visualize such as NaCl. We know Cl is -1 and as a whole it is negative so Na must be +1. Try thinking like this so if Cl2 add up to -2 then the brackets should be +2 and then break it down further to find the TM cation charge.