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+ Solution chemistry
+ Applied organic chemistry
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Aaron Weinberger

What is the procedure to completely dissolve HMTA (hexamine)...

Bennett Eberle  Follow

Thank you dear Mr. Aaron Bloomfield. Its analytical grade HMTA. When I only mix HMTA in water it completely dissolved within few seconds. But when I mix Zinc nitrate in that solution then HMTA appeared as dust like and remained ppt in the bottom. Is is due to the appearance of zinc nitrate? Plz help me.    

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Bruce Heath  Follow

Solubility of HMTA in water is quite high (about 800g/L) so I recommend stirring longer/more vigorously. You could also try mild heating or sonication to increase the rate of dissolution.
Is it possible that there is an insoluble impurity in the HMTA? How much remains undissolved?

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Brainfarction  Follow

Solubility of Zinc nitrate in water is high (~300g/100ml), so I think the problem is Zinc hydroxide. Solubility product constant of Zn(OH)2 is 3×10-17.  It meant solution 45mM zinc nitrate will be precipitated at pH 6 in hydroxide form. So you can use more HMTA, because Zn(OH)2 can dissolve in basic solution, but at this time you get solution of ZnO2- or complex of Zn(OH)2 and amine. Why don't you use the buffer HMTA?

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Alexander Mathey  Follow

You can try strring longer also heatimg more than room temperature

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