# Homework Help: Charge of NOS

1. May 7, 2015

### mooncrater

1. The problem statement, all variables and given/known data
There is a reaction given in my textbook which says:
$Na_2S+Na_2 [Fe(CN)_5 (NO)]$ $\longrightarrow$ $Na_4 [Fe (CN)_5 (NOS)]$
I know initially Fe is in +2 state.
But does it become +3 charged after the reaction? What is the charge on NOS? Is it $NOS^{-1}$ or $NOS^{-2}$?

2. Relevant equations

3. The attempt at a solution
I don't know.... charge on $Fe$ depends upon the charge on $NOS$... which I don't know.
Any help appreciated.

2. May 12, 2015

### James Pelezo

I don't know how much I can help without getting castigated by admin, but I will risk it... The [Fe(CN)5(NO)] = -2 net charge and [Fe(CN)5(NOS)] = -4 net charge. Both are octahedral coordination structures with Fe+4 + 2e- => Fe+2 as the reduction and sulfur in Na2S is -2 charge being oxidized to So in the -NOS structure. Both -NO and -NOS have the same oxidation states = -1. Look up octahedral geometry, place CN (= -1 charge) on all points in the plane and one above the plane. The -NO and - NOS are each below the plane. With all the points -1 = -6 and Fe+4 in the reactant side = net -2 for the reactant anion. Draw the same structure with all points -CN and one -NOS => -6 again on the product side, but Fe in the product structure is +2. Then [(-6) + (+2)] = -4 for the product anion structure. Hope I don't get fussed at. Good luck.

3. May 12, 2015

### mooncrater

Thanks for your reply. I had some doubts:
$Fe$ has two stable states... $Fe^{+2}$ and $Fe^{+3}$. From where $Fe^{+4}$ came? Originally the compound has $Fe^{+2}$.

4. May 13, 2015

### James Pelezo

+2 and +3 oxidation states for iron are the most common, but actually, iron can have eight (8) oxidation states depending on the compound and structure it is associated with... Here's a link that may help on this... http://en.wikipedia.org/wiki/Iron ... Scroll down to 'Atomic Properties', there will be a list of the possible oxidation states for iron.

Did you look up the octahedral geometry for coordination compounds? Follow my suggestion about placing the substrates as suggested, then check the net charges.

5. May 13, 2015

### James Pelezo

Here's Iron in an Octahedral Geometry for FeCl3-. The [Fe(CN)5(NO)]2- and [Fe(CN)5(NOS)]4- follow the same configurations.

Last edited: May 13, 2015
6. May 13, 2015

### James Pelezo

Hey guy, how you doing on the problem? Just checking if all is OK. Hope I've helped. jp

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