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Topic: Unknown Compound  (Read 21332 times)

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Offline UnintentionalChaos

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Re: Unknown Compound
« Reply #15 on: June 05, 2007, 03:08:21 PM »
Is it possible that you have a borate? I can find very little on ammonium borate, property-wise, but a borate would explain some of the things going on. Crackling during flame test could be due to a hydrate.

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Re: Unknown Compound
« Reply #16 on: June 05, 2007, 03:47:41 PM »
That's what my hint with ethanol & sulfuric acid was about ;) Boric acid esters burn green.

I think this method of borates determination was discussed or at least listed at chemicalforums.
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Offline ardyduh1manparty

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Re: Unknown Compound
« Reply #17 on: June 05, 2007, 04:31:35 PM »
well today i tested my chemical again and I'm pretty sure the cation is barium. I did several flame tests comparing how the aqueous solution of my unknown burned to other barium solutions and they were remarkably simmilar.
So assuming its barium and considering the following observations, what do you guys suggest?:
-soluble in water (about 22g/100 mL @ 25C)
-saturated solution is basic
-does not have a sulfate, sulfide, phosphate anion or halides.
-yellow precipitate w/ Nessler's reagent
-forms white precipitate w/ 6M NaOH
-when heated it decomposed to form water and a grayish gas
-white precipitate with AgNO3 solution

I was thinking maybe barium hydroxide since that is soluble in water and basic but im not sure what gas that was when i heated it (btw it stung the nostrills)

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Re: Unknown Compound
« Reply #18 on: June 05, 2007, 04:49:47 PM »
How do you test (chemically) for barium?

Ba(OH)2 - although strong base - is not that soluble.
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Offline ardyduh1manparty

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Re: Unknown Compound
« Reply #19 on: June 05, 2007, 09:07:01 PM »
A flame test by dipping a wand into a solution of barium chloride then putting it in the flame, and the same with the unknown solution. Both burned oractically exactly the same.

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Re: Unknown Compound
« Reply #20 on: June 06, 2007, 02:42:39 AM »
A flame test by dipping a wand into a solution of barium chloride then putting it in the flame, and the same with the unknown solution. Both burned oractically exactly the same.

This is not a chemical test. Think in terms of precipitation.
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Offline stamba

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Re: Unknown Compound
« Reply #21 on: June 14, 2007, 08:39:17 PM »
Your results are sooooooo confusing...
Try adding a bufer so that the pH value is about 5 (acetic bufer) and add soduim sulphate. If a white precipitate forms, then you really have barium cation.

Now, about the anion: What anion can you get? Any?
It may be a posphate, so it would be possible that they gave you
                Ba(NH4)PO4. Could it?

Chlorides can give the same smell as acetic anion if they are in large concentration.
The reaction with AgNO3/NH3/HNO3 giving the white precipitate, can be Cl- but could be carbonates, too. When you dissolve your solid substance in strong acid, what happens? Can you see large bubbles?

Oh, and anions CAN NOT give flame tests. They can't color the flame!

Offline ardyduh1manparty

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Re: Unknown Compound
« Reply #22 on: June 21, 2007, 12:25:16 PM »
this is a little late in comming but i ended up getting it right. It was barium acetate monohydrate. i found out that the nesslers reagent was faulty as it was contaminated with some other chemical as it was very basic when i tested the pH of it out of curiosity.

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