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Topic: Iron (II) and Potassium permanganate reaction  (Read 4838 times)

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Offline T

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Iron (II) and Potassium permanganate reaction
« on: July 30, 2015, 05:11:38 AM »
Hello,

The question is:

Fe2+ reacts in a 5:1 molar with a solution containing KMnO4- and dilute sulfuric acid. What is the reaction equation? Omit spectator ions.

So firstly the spectator ion is K+ so omit that. However, I don't understand what the sulfuric acid is doing? Is it a catalyst or something else? Thank you.

(mod edit to title, sjb)
« Last Edit: July 30, 2015, 12:02:49 PM by sjb »

Offline DrCMS

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Re: Iron (II) and Potassium permanganate reaction?
« Reply #1 on: July 30, 2015, 05:46:37 AM »
Hint - acids are a source of what ions?

Also your question title is misleading try to give better descriptions of the question such as "Iron (II) and Potassium permanganate reaction?"


(mod edit to title, sjb)
« Last Edit: July 30, 2015, 12:03:09 PM by sjb »

Offline T

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Re: Iron (II) and Potassium permanganate reaction
« Reply #2 on: July 31, 2015, 02:53:25 AM »
Ok, will try to make better titles from now on (could a moderator tell me what the original title was so I can see the difference?); acids are a source of hydronium ions. So it could bond with the permanganate, forming HMnO4. Thanks DrCMS

Offline sjb

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Re: Iron (II) and Potassium permanganate reaction
« Reply #3 on: July 31, 2015, 03:41:59 AM »
Ok, will try to make better titles from now on (could a moderator tell me what the original title was so I can see the difference?)

I forget exactly, but it was something like "Find the element"

Online Hunter2

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Re: Iron (II) and Potassium permanganate reaction
« Reply #4 on: July 31, 2015, 04:35:10 AM »
The point is still not found. Hint redox reaction.

Offline T

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Re: Iron (II) and Potassium permanganate reaction
« Reply #5 on: July 31, 2015, 06:01:39 AM »
I see.

For the redox reaction:
Fe2+  :rarrow: Fe3+ + e-

I am not sure about the reduction of MnO4-

MnO4- + 5e- + 8H+ :rarrow: 4H2O + Mn2+?

Thanks

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Re: Iron (II) and Potassium permanganate reaction
« Reply #6 on: July 31, 2015, 06:09:24 AM »
Everything is correct.

Offline T

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Re: Iron (II) and Potassium permanganate reaction
« Reply #7 on: July 31, 2015, 06:17:48 AM »
I see thanks. However what does the dilute sulfuric acid do?

Online Hunter2

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Re: Iron (II) and Potassium permanganate reaction
« Reply #8 on: July 31, 2015, 06:36:38 AM »
I think this you should answer yourself now. Look the redox reaction. What happens to the H+.

Offline T

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Re: Iron (II) and Potassium permanganate reaction
« Reply #9 on: July 31, 2015, 08:06:30 AM »
I see. So if I had NaOH instead of sulfuric acid the permaganate wont react with the iron?

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Re: Iron (II) and Potassium permanganate reaction
« Reply #10 on: July 31, 2015, 08:21:18 AM »
In case of alcaline conditions also it will react. But instead of Mn2+ MnO2 will be formed. In this case water reacts: H2O + (O) + 2 e- => 2 OH-

(O) is the oxygen in the oxidieser here Permanganate

Iron will also precipitate as Fe(OH)2 which is sensitive to oxygen and easily convert to Fe(OH)3

Offline Borek

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Re: Iron (II) and Potassium permanganate reaction
« Reply #11 on: July 31, 2015, 08:27:42 AM »
In the alkaline solutions permanganate gets reduced to manganate, MnO2 is produced closer to the pH 7.

This is just a rule of thumb though, sometimes you will get a mixture of products.
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Re: Iron (II) and Potassium permanganate reaction
« Reply #12 on: July 31, 2015, 08:35:49 AM »
This is in my opinion right, if no reducing agent is present. In present of reducing agent (maybe iron-II is not the best on), like Sulfite, Oxalate, etc. Manganaese dioxide will be formed. This will also happen with Manganate -VI and Manganate -V

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