Knowing oxidation states

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CHEM 14B Lover
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Joined: Fri Sep 28, 2018 12:19 am

Knowing oxidation states

Postby CHEM 14B Lover » Tue Feb 26, 2019 3:21 pm

In HW, 6L 1.9, it says the balance the reaction between potassium permanganate and iron2 chloride. How do we know the change in manganese's oxidation state (from +7 to +2)? Should we just know? +7 is deducible but not +2 (I think).

aisteles1G
Posts: 117
Joined: Fri Sep 28, 2018 12:15 am

Re: Knowing oxidation states

Postby aisteles1G » Tue Feb 26, 2019 3:28 pm

You have to look at the charge of the atom it's paired with so KMnO4 is +7 bc k is +1 and 0 is -2*4=-8 and the overall charge of the compound is zero so Mn has to be +7 to cancel the others out to zero. I'm not sure what the +2 compound is that you're referring to bc i dont have the book with me but if it's MnO then O is -2 so Mn has to be +2 to make the overall charge 0 of the compound. Hope this helps!

Emily Huang 1E
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: Knowing oxidation states

Postby Emily Huang 1E » Tue Feb 26, 2019 3:33 pm

You have to look at what Manganese is bonded to.KMnO4 is the compound and based on the periodic table we know the oxidation state of K is 1+ and the oxidation state of O is 2-. You can figure out an unknown oxidation number by knowing the oxidation number of the element it is bonded to


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