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Topic: Test for iron 2+  (Read 4030 times)

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Offline LeFowl

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Test for iron 2+
« on: February 10, 2009, 09:29:01 AM »
We did a lab testing on iron 2+ ions and this is what we did
FeCl2(aq)  + KMnO4(aq)---->?
we have to find out whats the reaction can someone help me???

Offline Astrokel

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Re: Test for iron 2+
« Reply #1 on: February 10, 2009, 09:36:07 AM »
KMnO4 is a strong oxidizing agent and able to oxidize Fe2+ to Fe3+. What condition did you carried out this reaction?
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Offline LeFowl

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Re: Test for iron 2+
« Reply #2 on: February 10, 2009, 09:42:59 AM »
KMnO4 is a strong oxidizing agent and able to oxidize Fe2+ to Fe3+. What condition did you carried out this reaction?
all we ever told was that FeCl2 in dilute HCl was added to KMnO4 in water and if the KMnO4 was decolourized (which it was)that it is Fe2+ was added and not Fe3+

Offline Donaldson Tan

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Re: Test for iron 2+
« Reply #3 on: February 18, 2009, 07:06:23 AM »
Wow.. as long as you don't add too much aq. KMnO4 into your test solution, you will observe a colour change from green to yellow as Fe2+ oxides to Fe3+. If you add excess aq. KMnO4, your entire test solution will just turn purple. I will provide you with 2 redox equations. You do the balancing yourself to arrive at the final chemical equation:

Assuming acidic conditions,
1) Fe2+ -> Fe3+ + e-
2) MnO4-  + 8H+ + 5e- -> Mn2+ + 4H2O

(If you use alkali aq. KMnO4 instead of acidified aq. KMnO4, you would observe a brown precipitate, ie. Fe(OH)3, formed)
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