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Author: Subject: phosphomolybdic acid synthesis
Karkov
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[*] posted on 10-4-2019 at 07:28
phosphomolybdic acid synthesis


When synthesizing PMA why does it sometimes change to green and sometimes yellow? I have done several experiments but can not find a correlation on why it’s doing that when each experiment is the same.

[Edited on Apr04-10-2019 by Karkov]
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CharlieA
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[*] posted on 10-4-2019 at 16:16


Molybdenum exhibits many oxidation states with, generally, characteristic colors. See for example https://en.wikipedia.org/wiki/Molybdenum#Chemical_properties... Is the preparative procedure that you are following published? If so, does it suggest the colors of various possible products or by- products?
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j_sum1
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[*] posted on 10-4-2019 at 20:50


Green??

Blue phosphomolybdates are famous -- often referred to as molybdenum blue, although this title serves a wide range of different species. Their structures are really interesting and have very high molecular mass and are extremely vivid in colour. Thus they serve as a means for titrating phosphate compounds.
My guess is that you have some of these included in your mixture -- probably as a result of something reducing the yellow compound.




If you are interested, take a look at the latest offering from sum_lab:
A primer on metals and non-metals with at least one novel experiment.
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