Redox titration help!?

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shiva300
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#1
Report Thread starter 8 years ago
#1
Okay so I'm probably being an idiot as usual... but I'm so confused, doing q's on redox etc and the text book says the end point of the titration:8H+ + MnO4- + 5Fe2+ = Mn2+ + 4H2O + 5Fe3+


is PURPLE!!!
Mn2+ is pink and Fe3+ is orange!?!?
please someone explain how this is apparently purple
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Borek
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#2
Report 8 years ago
#2
Iron is barely visible (or masked with phosphoric acid), what you see is the excess of permanganate.

http://www.titrations.info/permanganate-titration-iron
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shiva300
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#3
Report Thread starter 8 years ago
#3
but it's being changed from permanganate to mn2+ which would be purple to pink? excluding the iron shouldn't the end point be pink?


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Borek
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#4
Report 8 years ago
#4
No, EXCESS permanganate changes the color of the solution. Neither Fe(III) nor Mn(II) have color strong enough to be seen before the end point, but once you add a slight excess of permanganate it will color the solution.
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