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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Albacoide on May 01, 2013, 10:18:52 AM

Title: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Albacoide on May 01, 2013, 10:18:52 AM

Hello, I'm a chemical engineering student and need to prepare a Methylene Blue solution (1ml = 0.01 meq), or 0.01N, from powder.
To calculate the amount of powder required I need the Methylene Blue's equivalent weight or equivalent numbers, but haven't been able to find it so far.
Sorry if this is the wrong forum.
Help appreciated.

Title: Re: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Arkcon on May 01, 2013, 02:38:53 PM

OK, so for your application, 0.01 milliequivalents is the same as 0.01 N, as you described in your first statement.  So, do you know the definition if N, as in, how to compute it?

Title: Re: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Albacoide on May 01, 2013, 03:36:48 PM

Yes, in my case:

0.01 N = MB grams/ equivalent weight = MB grams x Z/ Molar mass
where Z is the equivalent number (not sure if that's how it's called in english) for MB. (number of H⁺ OH^-, etc, depends on the substance).

So I need either the equivalent number Z or the equivalent weight soI could determine the grams I need.

Title: Re: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Arkcon on May 01, 2013, 05:51:59 PM

Well, it seems to me that you declared the mEq = normality at the top of your original post.  But anyway, to determine equivalents, you'll need to describe the reaction you'll be performing, and need to know the structure of methylene blue.

Title: Re: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Albacoide on May 01, 2013, 07:17:52 PM

From now on MB: methylene blue. ;D

It will be used to determine the methylene blue index of pet coke, by its addition to a solution of pet coke acidified with sulfuric acid.
So the reaction is between MB and sulfuric acid.

Title: Characterization of activated carbon. Methylene blue index.
Post by: Albacoide on May 05, 2013, 04:02:02 PM

Hello, I need to determine the methylene blue index of activated carbon, does anyone has the procedure or know where to find it?

Thanks.

Title: Re: Preparing a Methylene Blue solution. Need MB Equivalent Weight.
Post by: Arkcon on May 06, 2013, 07:11:09 PM

Albacoide:, I've gone ahead and merged you repeat question with your old thread covering the same topic, and moved it to Analytical Chemistry.  I'm sorry you haven't had good results so far, and maybe someone will come by to help you soon.  For starters, can you try Googling for this question, to see if the analytical test you need is easy to find?  And can you look at the test you find to see if its what you need, and that you can understand the techniques?