Takron
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Strange series of events...what happened.
I was setting out to make ammonium chloride and bought some store ammonia and a gal container of 11M HCl acid. I titrated the ammonia solution and it
was 3% so I took and made 3 batches of 900mL of the ammonia to 100mL of the acid. I did this 3 times and put it into a 3L boiling flask. I added
boiling chips as ammonia bumps something fierce when you boil it and the stones started reacting to my access of acid, so I added some ammonia to stop
the reaction. The surfactant they put into the store ammonia was causing some fierce bubbles so I added some SiO2 in the flask to control the bubbles
but it would only last for about 30 min and I would have to add more. Twards the end of the reduction, the solution turned green and then a deep
yellow and had a very strong chlorine smell. I thought it was some of the NH4Cl decomposing, but when I precipitated the salt by cooling and
filtering, the salt was a very gooey yellow mess. I figured it was because of the hygroscopic nature of NH4Cl, so I put it into my dessication chamber
with some silica gel and let it dry. Now my silica gel is all turned red but I don't have moisture indicating silica gel and my salt is not dry but
still a yellow mess of gel.
It was an odd series of events that led to this and I was wondering if anyone might have an idea of what I may have as I think the boiling stones and
the SiO2 I put in to control the bubbles reacted somehow because I had to boil this thing for almost 2 days.
[Edited on 7-11-2011 by Takron]
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woelen
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What purity do your chemicals have? Is the hydrochloric acid colorless or yellow? Hydrochloric acid must be colorless like water, but in practice, the
acid frequently is yellow, especially when purchased from hardware stores. The ammonia also may contain impurities, even if it is colorless.
Boiling stones and SiO2 do not react with these chemicals.
Pure NH4Cl is white like snow and consists of small crystals. It is somewhat hygroscopic, but it certainly does not form a gel-like mass. Your
material must contain a lot of impurities, probably coming from the ammonia (which may contain surfactants, detergents and other crap) and the acid
(if it has a yellow color).
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Takron
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Quote: Originally posted by woelen  | | Your material must contain a lot of impurities, probably coming from the ammonia (which may contain surfactants, detergents and other crap) and the
acid (if it has a yellow color). |
After another day in the dessication chamber, I have come to find that after multiple washes in acetone, the crystals are now 98% white and most all
the yellow has been washed away, along with the surfactants, as my vacuum flask is all bubbly now. The gel is gone and this has also given me insight
into why my phthalic anhydride reaction failed. Its the same yellow junk that ruined my anhydride cook. Since my acid was the same in both of these
instances, I'm thinking my acid is to blame.
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