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Topic: Redox titration-iron  (Read 5048 times)

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Offline treelove

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Redox titration-iron
« on: May 10, 2009, 06:38:54 PM »
I did a titration using potassium permanganate in water and my iron sample dissolved in sulfuric acid. I also used phosphoric acid to make the color change more visible. I found that the average volume I used was 25.7 mL, and then I found that I had used 5.14x10-4 moles of KMnO4. The equation I wrote out is this:
Fe+2 + 8H+ + MnO4- + 5e- :rarrow: Mn+2 + 4H2O + Fe+3 + e-

Is that right? Or should I do 4e- on the left and omit the electron on the right? Do I need to include the phosphoric or sulfuric acid somehow, or is that covered by the H ions?

I'm not really sure where to go from here to determine the percent of iron though, since I have the moles of KMnO4 instead of just MnO4-, will that alter my results?
Sorry I really have never done this before and we haven't gone over it in class so these questions might sound kind of stupid.

Offline treelove

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Re: Redox titration-iron
« Reply #1 on: May 10, 2009, 08:03:03 PM »
Ok that equation is wrong, I think I got the right one now. I ended up getting about 14.35% Fe, will anyone confirm this answer? What compound could this be?

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Re: Redox titration-iron
« Reply #2 on: May 11, 2009, 03:25:29 AM »
I got 92%, but I am not sure I have used the same sample mass  :P

We can't check your numbers not knowing all the relevant data.
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Offline treelove

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Re: Redox titration-iron
« Reply #3 on: May 12, 2009, 12:55:56 AM »
what other information do you need?

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