How to Make Aluminum Nitrate Nonahydrate


Uploaded by NurdRage on 27.11.2009

Transcript:
Greetings fellow nerds.
In this video we're going to make crude aluminum nitrate
nonahydrate that we'll need in upcoming videos.
At first, you might think we can just add aluminum directly to nitric acid.
Unfortunately, as seen here, aluminum does not react with nitric acid due
to a passivation layer that forms on the surface.
We need to go through a roundabout method to get to aluminum nitrate.
First start with 20 mL of a 6 Molar solution of hydrochloric acid.
This can be made by mixing equal amounts of concentrated hydrochloric acid
and distilled water. Then drop in 1g of aluminum foil.
As you can see, aluminum reacts very vigorously with hydrochloric acid.
This will produce aluminum trichloride. Now we want aluminum nitrate so to convert
it, we add 20mL of concentrated 15.6 molar nitric
acid. The nitric acid reacts with the chloride ions
in the aluminum trichloride and oxidizes them to nitrosyl chloride.
This bubbles out of solution and leaves behind aluminum nitrate.
This gas is rather toxic and the mixture should be left in a fumehood or outside to dry.
The conversion from chloride to nitrate will proceed on its own.
To speed up the reaction you can also boil the mixture.
The brown gas is the nitrosyl chloride decomposing and producing nitrogen dioxide and chlorine.
You can tell when the reaction is over when the gas clarifies,
indicating it's no longer producing nitrosyl chloride and nitrogen dioxide.
At this point, take it off heating and once again let it dry.
You may need to use the desiccator bag we showed you in a previous video.
I found the desiccator bag was a must have in the summer when the ambient humidity was
high.
You cannot simply boil down the mixture because aluminum nitrate decomposes if heated
when dry.
Now when it is dry, it should be a white solid. If it's a yellow solid it means there is still
leftover chloride in the product and you should add more nitric acid and water
to completely react it.
Now another point, you might run into the situation where the
solution doesn't crystallize even after a couple of weeks.
Similar to hot ice you need to initiate it. The best way i found was to simply connect
an air hose or a strong fan and blow air into the mixture, accelerating
drying and initiating crystallization. Once it's initiated put it into the desiccator
bag for complete drying.
Eventually, you'll have crude aluminum nitrate nonahydrate.
It's not pure enough for our purposes, but we'll show purification techniques in
an upcoming video.
Before you get any ideas, you CANNOT use aluminum nitrate nonahydrate
for pyrotechnics. Here is a mixture of sugar and aluminum nitrate
nonahydrate. As you can see, it doesn't burn,
but instead turns into this rubbery mass of carbon and aluminum oxides.
Instead we'll be using aluminum nitrate nonahydrate to make glow in the dark powder.
Thanks for watching, please subscribe rate and comment.
Oh and before you ask why can't you just mix both acids.
The answer is you could, but the combined acids partially decompose
before they react with the aluminum. So you'll end up wasting more acid in order
to dissolve the same amount of foil. Therefore, to save costs,
you have to go through the two step method in order to make aluminum nitrate.