Oxidation Number

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Tamera Scott 1G
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am

Oxidation Number

Postby Tamera Scott 1G » Mon Nov 26, 2018 1:02 pm

Today Lavelle mentioned that the oxidation state of Fe in the formula [Fe(CN6)]4- is +2. How did we conclude to that?

Cody Do 2F
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

Re: Oxidation Number

Postby Cody Do 2F » Mon Nov 26, 2018 1:12 pm

Hey Tamera!

We know that the entire compound [Fe(CN)6] has a overall charge of -4. We also know that CN has a charge of -1 (Simply from making the lewis diagram and counting all the charges, etc.). The compound [Fe(CN)6) has 6 CN molecules, thus giving it a charge of -6. Now we ask ourselves what value is needed to go from -6 to -4. This value is +2. Thus, the charge of Fe must be +2.

AlyssaBei_1F
Posts: 99
Joined: Fri Sep 28, 2018 12:17 am

Re: Oxidation Number

Postby AlyssaBei_1F » Mon Nov 26, 2018 1:16 pm

How do we know [Fe(CN)6] has an overall charge of -4? Is it given?

Cody Do 2F
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

Re: Oxidation Number

Postby Cody Do 2F » Mon Nov 26, 2018 1:21 pm

Yeah, the overall charge of -4 is given by the superscript placed after the end square bracket!

[Fe(CN)6]-4 would mean that the entire [Fe(CN)6] compound has a overall charge of -4 and thus Fe would have an oxidation state of +2.

If it were [Fe(CN)6]-3 instead, then the entire [Fe(CN)6] compound would have an overall charge of -3 and thus Fe would have an oxidation state of +3 (as there are six negative charges given by the 6 CN molecules and an overall charge of -3).

Tamera Scott 1G
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am

Re: Oxidation Number

Postby Tamera Scott 1G » Mon Nov 26, 2018 6:07 pm

How do you figure out that CN has a -1 charge? I tried drawing out the lewis structure but did not get that answer.


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