Chemistry_Keegan
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Seperation Of Three Sodium Compounds
Hello everyone. I have a clear solution of sodium aluminate, sodium nitrate and sodium chloride, and would like to separate the three individual
chemicals. Does anyone have any idea on how I should go about doing this? I would prefer that the methods only use household items, but feel free to
post other methods as well, because I will probably find them interesting anyway. I am planning on evaporating all the water away, but if for some
reason you don't think I should, just tell me and I will leave it as is.
[Edited on 17-2-2013 by Chemistry_Keegan]
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elementcollector1
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separate out the chloride by precipitation with a soluble silver or lead compound, the aluminate by adding a small amount of acid and alcohol (should
break the double salt to the acid salt of the sodium and aluminum, then add base to precipitate the aluminum as hydroxide). Finally, separate the
nitrate by adding KCl and chilling - this will precipitate KNO3.
Where did you come across such a peculiar solution of salts?
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Chemistry_Keegan
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I reacted a pop can with Crystal Drāno, which is a mixture of sodium hydroxide, sodium nitrate, sodium chloride and aluminium. Once I added
water, the dissolved sodium hydroxide and the aluminium from the can performed this somewhat famous reaction:
2 NaOH + 2 Al + 2 H2O = 2 NaAlO2 + 3 H2
So after letting the liquid settle and filtering off any gunk left over from the reacted can, I was left with what I believe to be a solution of the
three compounds mentioned above. Unless I am missing something. Is it possible any other reactions occured? In my research I read that that the sodium
nitrate is just there to catch the excess hydrogen in the process of cleaning drains, to prevent any combustion hazard. As for the sodium chloride, I
read it's just there for aesthetic purposes (they color it blue). Oddly enough, the final solution is completely clear and there is absolutely no sign
of the blue color. What do you suppose they used to color it and what do you think happened to it? Anyway, if any other reactions may have occurred,
please feel free to tell me.
[Edited on 17-2-2013 by Chemistry_Keegan]
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Chemistry_Keegan
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Just as a little update, I recently found out that the dye used in the Drāno Crystals is Copper Phthalocyanine Green, if that helps any.
[Edited on 23-7-2013 by Chemistry_Keegan]
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papaya
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If you reacted it with Al then you've probably lost most of the nitrate - as you mentioned it can be reduced to nitrite.
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ScienceSquirrel
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Your best strategy for getting something useful out of Drano might be to remove the aluminium by sieving or by hand.
Then dissolve the salts in hot water and add Lo Salt or potassium chloride.
This should produce reasonably pure potassium nitrate, one recrystallisation and you should have some neat and useful stuff. The rest can go down the
drain or in the trash.
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Chemistry_Keegan
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Ah yes, I actually never knew exactly how the nitrate interacted with the hydrogen, but now I understand. I found this reaction:
2 NO3- + 9 H2 → 2 NH3 + 6 H2O
It states that the nitrate and the hydrogen are transformed into ammonia and water. Just one question, what happens to the sodium?
Quote: Originally posted by ScienceSquirrel  | | Your best strategy for getting something useful out of Drāno might be to remove the aluminium by sieving or by hand. Then dissolve the salts in
hot water and add potassium chloride. This should produce reasonably pure potassium nitrate, one recrystallisation and you should have some neat and
useful stuff. The rest can go down the drain or in the trash. |
I am more interested in separating the finished reaction mixture that I currently have, rather then trying to get a useful chemical from the original
Drāno Crystals, but I am sure that this method of making potassium nitrate will come in handy later. So, as my last question for now, what do you
guys think the composition of the reaction mixture really is? Right now I'm thinking water, ammonia, sodium aluminate, sodium chloride and a compound
that includes the sodium ions from the reacted sodium nitrate. This once again brings me back to my last question, what became of the sodium ions?
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woelen
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The sodium ions did not react, they are still there in solution.
You could try to obtain aluminium hydroxide from your liquid by adding acid to the liquid such that first a precipitate is formed and then is
redissolved again. Then add excess amount of ammonia. A new precipitate is formed and all of your aluminium drops out as Al(OH)3. This can be filtered
and rinsed and then you can add some acid to make the aluminium salt. Easiest is to make the sulfate, but the chloride (hexahydrate) also is possible.
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Bezaleel
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| Quote: Originally posted by Chemistry_Keegan | | So, as my last question for now, what do you guys think the composition of the reaction mixture really is? Right now I'm thinking water, ammonia,
sodium aluminate, sodium chloride and a compound that includes the sodium ions from the reacted sodium nitrate. This once again brings me back to my
last question, what became of the sodium ions? |
In an alkaline solution, NH4+ will always be in equilibrium with NH3 and H2O. Therefore, if ammonia really formed, you should have smelled it. Did
you?
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Chemistry_Keegan
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But the way it looks right now, it seems that there is a surplus of positive ions because of the sodium. If I where to evaporate all the water away,
what negative ion would balance it? Hydroxide? And thank you for that method of creating an aluminium salt, I will definitely use that in the future.
| Quote: Originally posted by Bezaleel | | In an alkaline solution, ammonium will always be in equilibrium with ammonia and water. Therefore, if ammonia really formed, you should have smelled
it. Did you? |
Oh yes, the reaction mixture sure has a smell. When I first made it, I had never smelt ammonia on it's own before, so I wasn't sure where the smell
was coming from (especially before I knew ammonia was even formed) and assumed it was the sodium aluminate, because I knew the other ingredients
didn't have a smell, and it was my first experience with the chemical. But this makes allot more sense to me now.
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