coursework help

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wannabeaditz
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coursework help

Post by wannabeaditz » Tue Apr 24, 2007 4:18 pm

does anyone know what the pH of methylene blue is?
i've looked all over the internet but can't find it anywhere!

blcr11
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Post by blcr11 » Tue Apr 24, 2007 7:33 pm

I'm not sure how to answer this without being confusing. Methylene blue is not a pH indicator in the same sense that, say, phenolpthalein is with its characteristic color change between pH 8-9. Methylene blue does have a color change, but rather than being strictly pH-dependent, it is a function of the redox status of its environment. If it is under a net reducing environment, it will be a colorless, reduced compound. Under a net oxidizing environment it will be a blue, oxidized compound. That's not to say that the redox environment can't be linked to the pH in some way, but it's the redox status that counts moreso than the pH, per se.

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Post by yagetme » Sat Apr 28, 2007 4:59 pm

Hi all! im really stuck on this AS cswk im nt sure wht to write on the preliminary testing. This is the cswk to do with yeast cells. Can ANYONE PLZ help me with this section of the cswk THANK U

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wannabeaditz
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Post by wannabeaditz » Sun Apr 29, 2007 5:48 pm

didn't you do premilinary work in class
we had to do tests to see how much meth blue to use because it is in too high a concentration, what temperature range to use so we can get a good graph etc. Hope that helped
Elisah xx

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biology cswk

Post by yagetme » Sun Apr 29, 2007 6:22 pm

yea it did help thanks. Im jus wonderin wht happenes if the conc of the methyl blue is to high

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wannabeaditz
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Post by wannabeaditz » Mon Apr 30, 2007 10:02 am

then the colour won't change properly and the solution will be dark blue
Elisah xx

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Post by david23 » Sun May 06, 2007 5:32 am

u cant find pH like this, please read the definition of pH again. I think u are looking for another value that is actually constant

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