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Topic: Finding concentration of H2O2 by redox titration.  (Read 25745 times)

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Offline Borek

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Re: Finding concentration of H2O2 by redox titration.
« Reply #15 on: April 26, 2009, 08:52:55 AM »
Sorry, I have not noticed you were referring all the time to manganate. That's strange, I have never heard about manganate being used in potentiometric titration, are you sure that's what you are asked/plan to do?
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Offline upsidedown

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Re: Finding concentration of H2O2 by redox titration.
« Reply #16 on: April 26, 2009, 09:13:24 AM »
Thanks for helping me Borek.

Yes, the plans says:
"One of your experiments should involve a redox titration with potassium manganate (VII)."

The plan also says that I have to used the end-point colour change to explain the redox chemistry in the titration reaction. I know that no indicator is required beacuse it should turn pink/purple from clear, but im unsure how to  explain the redox chemistry in the titration reaction. 

Offline Borek

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Re: Finding concentration of H2O2 by redox titration.
« Reply #17 on: April 26, 2009, 09:35:30 AM »
Well, manganate (VII) is just a permanganate.

No need for indicator:

http://www.titrations.info/potentiometric-titration-end-point-detection

Not sure what

explain the redox chemistry in the titration reaction

means, other than what is already obvious from the reaction equation.
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Offline upsidedown

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Re: Finding concentration of H2O2 by redox titration.
« Reply #18 on: April 26, 2009, 09:53:16 AM »
In my second experiment I will be doing a gas collection, which seems easy enough, just add a metal oxide, messure O2 released, then work out the conc of H2O2.
The only problem is that this will give me different concentration from the first experiment, because all measurements are predictions. Do you know if this is acceptable in plans?

Offline victoria_kay

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Re: Finding concentration of H2O2 by redox titration.
« Reply #19 on: May 09, 2009, 11:19:31 AM »
I am also doing this plan... and I'm glad to hear I'm on the right lines because nobody at my college seems to have a clue with what they're doing.

I know that I need to dilute the hydrogen peroxide... but I do not know how. In other titrations I have used a 250cm³ volumetric flask to put 25cm³ of the solution being titrated in and then filled the rest up with distilled water or acid. Is it the same with this titration? Should I use 25cm³ of hydrogen peroxide? And how can I calculate the concentration of potassium permanganate to use?

Any help would be fantastic!

Offline Borek

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Re: Finding concentration of H2O2 by redox titration.
« Reply #20 on: May 10, 2009, 04:24:50 PM »
Permanganate commonly used in labs is 0.1M.

Not kowing - approximately - concentration of hydrogen peroxide, it is difficult to calculate dilutions. However, you should take into account optimum volume of titrant used - that is, your samples should contain enough hydrogen peroxide so that when titrating you will be using about 8o-90% of burette volue. That should allow backward calculation of dilution.
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Offline victoria_kay

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Re: Finding concentration of H2O2 by redox titration.
« Reply #21 on: May 11, 2009, 01:30:25 PM »
Thanks that was helpful :)

I have another question aswell... I am asked to describe another experiment to determine the concentration of the hydrogen peroxide. I know to do a gas collection of O2 from the catalytic decomposition of hydrogen peroxide. However I am asked to do a calculation before to determine how much hydrogen peroxide I should use in the decomposition. Obviously I have to take the capacity of gas syringe into account but I'm not sure whether to use the fact the hydrogen peroxide is "100-volume" to calculate this or use the equation 2H2O2 -> 2H2O + O2 will it make any difference?

Thanks again


Offline Borek

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Re: Finding concentration of H2O2 by redox titration.
« Reply #22 on: May 11, 2009, 02:00:37 PM »
Using 100-volume should give an instant answer.
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