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Topic: Redox Titration Question  (Read 4506 times)

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Offline Procrastinate

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Redox Titration Question
« on: June 07, 2010, 06:26:16 AM »
When Potassium Permanganate is titrated against Iron (II) sulphate solution, write the half equations:

I know that Potassium Permanganate has the formula:

5e- + 8H+ + MnO4- -> Mn2+ + 4H2O

However, I am not sure how to write Potassium Sulfate...I am confused as to what to do with that polyatomic ion. Polyatomic ions never oxidize right?

Offline Borek

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Re: Redox Titration Question
« Reply #1 on: June 07, 2010, 06:29:40 AM »
Spectators.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline cliverlong

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Re: Redox Titration Question
« Reply #2 on: June 07, 2010, 06:43:36 AM »
When Potassium Permanganate is titrated against Iron (II) sulphate solution, write the half equations:

I know that Potassium Permanganate has the formula:

5e- + 8H+ + MnO4- -> Mn2+ + 4H2O

However, I am not sure how to write Potassium Sulfate...
No potassium sulphate I can see in your original equation

As acidfied potassium permanganate is a strong oxidizing agent it will oxidize Iron(II) to Iron(III)
Quote
I am confused as to what to do with that polyatomic ion. Polyatomic ions never oxidize right?
Not true I think
If you consider mixing concentrated sulphuric acid with sodium bromide or sodium iodide , the hydrogen bromide or hydrogen iodide produced will reduce the sulphate to various products such as sulphur dioxide and hydrogen sulphide

http://www.chemguide.co.uk/inorganic/group7/halideions.html#top

Clive

Offline Procrastinate

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Re: Redox Titration Question
« Reply #3 on: June 07, 2010, 06:45:45 AM »
When Potassium Permanganate is titrated against Iron (II) sulphate solution, write the half equations:

I know that Potassium Permanganate has the formula:

5e- + 8H+ + MnO4- -> Mn2+ + 4H2O

However, I am not sure how to write Potassium Sulfate...
No potassium sulphate I can see in your original equation

As acidfied potassium permanganate is a strong oxidizing agent it will oxidize Iron(II) to Iron(III)
Quote
I am confused as to what to do with that polyatomic ion. Polyatomic ions never oxidize right?
Not true I think
If you consider mixing concentrated sulphuric acid with sodium bromide or sodium iodide , the hydrogen bromide or hydrogen iodide produced will reduce the sulphate to various products such as sulphur dioxide and hydrogen sulphide

http://www.chemguide.co.uk/inorganic/group7/halideions.html#top

Clive


Sorry, I meant Iron Sulphate.

However, from the response aforementioned, is it just:

Fe -> Fe2+ + 2e- since the SO4 is a spectator ion?


Thanks.

Offline AWK

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Re: Redox Titration Question
« Reply #4 on: June 07, 2010, 08:10:55 AM »
Quote
Fe -> Fe2+ + 2e- since the SO4 is a spectator ion?

Fe2+ =Fe3+ + e-
AWK

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