HamiltonMaya - 30-1-2021 at 08:24
I've successfully made ammonium perchlorate by electrolysis and double decomposition. But over the last week my perchlorate has turned slightly yellow
and is giving off an acidic smell. Redissolving some of it gives a pH of 5.8. I've gone back through all my notes and the sources I used, and I can't
work out exactly what's going wrong.
I used a titanium substrate lead dioxide anode to electrolytically form sodium perchlorate from sodium chloride. I filtered the solution, then added
hydrochloric acid until it reached pH1, and stirred it for an hour to destroy the remaining sodium chlorate. I then added sodium bicarbonate until it
reached pH7, to neutralize the acid. This was again stirred for an hour to allow the reaction to complete. I then added ammonium chloride to convert
the sodium perchlorate to ammonium perchlorate. The solution was chilled and then I filtered out the crystals.
Initially the crystals were a beautiful white with an ammonia smell due to the breakdown of ammonium bicarbonate (formed by the same double
decomposition as the perchlorate). After drying in my oven the smell stopped.
The perchlorate has been stored in a plastic box, which isn't as airtight as I would like, and it's taken up some moisture from the air.
Does anyone have any thoughts on where I could be going wrong?
Laboratory of Liptakov - 30-1-2021 at 10:22
Do you have any source where you bought the PbO2 anode? Your procedure looks perfect. Maybe is wrong in measurement pH during neutralisation. And your
product with pH5,8 is possible neutralised ammonia water? During drying process will NH3 out. And problems will off. Is possibe for neutralization
using ammonia water directly? Instead NaHCO3? After maybe will problem with separation NH4Cl?
HamiltonMaya - 1-2-2021 at 03:06
Thanks, I'll look into using ammonia water for my next batch. Producing NH4Cl shouldn't be too much of a problem, since I'm about to add loads of it
for the double decomposition anyway.
I got the anode as a gift from a friend who works in house clearance - I've no idea where it came from originally, and it seems to have been cut from
a larger sheet.
Laboratory of Liptakov - 1-2-2021 at 05:09
Thanks, for info about anode. Because availability PbO2 can be difficult for a lot researchers. Respectively quality PbO2 surface for a long using.