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Topic: How do I figure out (w/w) titrations?  (Read 7407 times)

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Offline taishar

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How do I figure out (w/w) titrations?
« on: April 11, 2010, 10:07:57 AM »
First off, let me thank anyone for the help. This is actually a problem for something I am having at work, but I can't find any good information on it. Your help is very much appreciated!

Ok, I am trying to get 30% (w/w) Hydrogen Peroxide. I am testing it against 0.1000N Potassium Permanganate in the ACS manual suggested manner. I know that 1 ml of KMnO4 = 1.701mg of H202.

Let us say that I weighed up 1.0000 grams of H202 in a beaker, added water, how would I figure this out? If someone could point me to the right formula then I should be able to get the rest of it :)


Thank you again!

Offline sjb

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Re: How do I figure out (w/w) titrations?
« Reply #1 on: April 11, 2010, 01:49:35 PM »
What is the balanced equation for the reaction you are carrying out?

Offline taishar

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Re: How do I figure out (w/w) titrations?
« Reply #2 on: April 11, 2010, 02:07:03 PM »
I believe this is correct as the formula?

% H2O2 (by weight) = [(mLs KMnO4) x (N) x (0.01701) x (1000)] / (grams of H2O2 sample used) where: N = Normality of the standardized potassium permanganate

I thought that was (w/v) though?

The balanced equation should be:

2 KMnO4 + H2O2 + 3H2SO4 ---> O2 + MnSO4 + K2SO4 + 4H20

Offline sjb

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Re: How do I figure out (w/w) titrations?
« Reply #3 on: April 11, 2010, 03:40:50 PM »
Where has the 0.01701 come from?

Offline Borek

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Re: How do I figure out (w/w) titrations?
« Reply #4 on: April 11, 2010, 04:02:02 PM »
I know that 1 ml of KMnO4 = 1.701mg of H202.

So after titration you can easily calculate mass of hydrogen peroxide in the sample, don't you?

Quote
Let us say that I weighed up 1.0000 grams of H202 in a beaker, added water, how would I figure this out?

Now you should titrate and use titre volume to calculate mass of hydrogen peroxide, then use definition of mass percentage.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline taishar

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Re: How do I figure out (w/w) titrations?
« Reply #5 on: April 11, 2010, 04:05:09 PM »
0.01701 — Weight of sulfuric acid which is equivalent to 1 ml of
sodium hydroxide VS (1 mol/L), g.

Offline taishar

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Re: How do I figure out (w/w) titrations?
« Reply #6 on: April 11, 2010, 04:06:33 PM »
Thanks Borek, so

% H2O2 (by weight) = [(mLs KMnO4) x (N) x (0.01701) x (1000)] / (grams of H2O2 sample used) where: N = Normality of the standardized potassium permanganate
 is the correct formula afterall! :)

Thank you both!

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