vmelkon
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alum reacts with steel
Does this make sense. The information is on this site and a friend wants to know if it works:
http://www.rwg.bz/board/index.php?showtopic=2765
Of course, I could give it a try since I have aluminum potassium sulfate.
Or is that food grade stuff ammonium aluminum sulfate. This stuff is a little acidic.
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careysub
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I have used boiling in potassium alum to dissolved a steel tap embedded in a block of aluminum. It left the threads that had been cut intact, and
saved the part.
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blogfast25
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ALL aluminium salts are a little acidic:
[Al(H2O)6]<sup>3+</sup>(aq) + H2O(l) < === > H3O<sup>+</sup>(aq) +
[Al(H2O)5(OH)]<sup>2+</sup>(aq)
Food grade or not...
[Edited on 7-1-2016 by blogfast25]
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DraconicAcid
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Blogfast, I think the OP thought the food-grade ammonium aluminum sulphate would be more acidic due to the ammonium ion, not because of the
food-gradeness of it.
Anyway, the aluminum ion is much more acidic than the ammonium ion.
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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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blogfast25
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Quote: Originally posted by DraconicAcid  | Blogfast, I think the OP thought the food-grade ammonium aluminum sulphate would be more acidic due to the ammonium ion, not because of the
food-gradeness of it.
Anyway, the aluminum ion is much more acidic than the ammonium ion. |
I didn't see the ammonium in that question (just woke up).
Like you said, makes no difference though in terms of acidity.
Ka for Al<sup>3+</sup>(aq) = 1.4 x 10<sup>-5</sup>
Ka for NH4<sup>+</sup>(aq) = 5.6 x 10<sup>-10</sup>
http://bilbo.chm.uri.edu/CHM112/tables/KaTable.htm
[Edited on 7-1-2016 by blogfast25]
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vmelkon
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Thanks dudes.
So, it sounds like almost any aluminum salt would do the job.
I assume the reaction produces iron hydroxide or aluminum hydroxide in the end.
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blogfast25
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In a nutshell, yes.
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vmelkon
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I tried it.
At first, there were tiny bubbles stuck on glass walls and iron. This was possibly hydrogen.
After 1 week, some Fe(OH)2 was visible on the bottom of test tube.
After another week, there is quite a bit of white precipitate. It is amorphous. It is possibly Al(OH)3 but the solution looks colorless. Weird.
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We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
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