Why can't you remove hydroxide from Al(OH)3 with alkali metals?

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In summary: It is not clear at all if such oxides can be produced by your reaction.In summary, the individual's initial idea of refining aluminum without fluorine using sodium or potassium to react with aluminum hydroxide is not feasible as the mixture of Al and NaOH is not thermodynamically stable. Additionally, the non-aqueous reaction between 4Na and 2Al(OH)3 may produce a mixed oxide such as Na2O·Al2O3. Further research is needed to determine the feasibility of this method.
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So I've tried to research a bit on refining aluminum without fluorine, and I came up with the idea of reacting the hydroxide off aluminum hydroxide with sodium or potassium. Only problem is, the reaction doesn't work, according to what I've found. I'm curious why, as the electronegativity table seems to indicate that Na or P should preferentially react with the hydroxide ions.

I appear to have a gap in my reasoning somewhere, so what am I missing?
 
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No idea what kind of reaction you are talking about, please write the reaction equation.
 
  • #3
If it worked, it would be 3Na + Al(OH)3 → Al + 3NaOH.
 
  • #4
OK

Electronegativities are not the only thing that matters. What matters is the thermodynamical stability of products. In this case mixture of Al and NaOH is not stable - Al nicely dissolves in the alkali producing sodium aluminate. In the presence of water reaction is (more or less)

2NaOH + 2Al + 2H2O → 2NaAlO2 + 3H2

When there is no water around situation gets more complicated, but you can still expect hydrogen to evolve and some kind of aluminate or mixed oxide to be produced. That's because Al is amphoteric, and its hydroxide can react both as an acid and as a base.
 
  • #5
So for the non-aqueous reaction, it would be something like, but not necessarily, 4Na + 2Al(OH)3 → 2NaAlO2 + 2NaOH + H2?
 
  • #6
I would check if there is no mixed oxide like Na2O·Al2O3 - which would be a most likely product then.

Many salts can be described as mixed oxides, and they are present in many minerals (see for example http://en.wikipedia.org/wiki/Spinel_group).
 
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1. Why can't you remove hydroxide from Al(OH)3 with alkali metals?

Al(OH)3 is a strong base and is highly stable, which means that it is difficult to break down its chemical bonds. Alkali metals, which are highly reactive, are not strong enough to replace the hydroxide ions in Al(OH)3.

2. Can other methods be used to remove hydroxide from Al(OH)3?

Yes, there are other methods that can be used to remove hydroxide from Al(OH)3, such as using strong acids or heating the compound to high temperatures. However, these methods may also result in the breakdown of Al(OH)3 into other compounds.

3. Is it possible to remove hydroxide from Al(OH)3 with alkali metals under certain conditions?

In theory, it is possible to remove hydroxide from Al(OH)3 with alkali metals under certain conditions, such as using a highly reactive alkali metal and a suitable solvent. However, in most cases, this reaction is not feasible or practical.

4. Why is it important to remove hydroxide from Al(OH)3?

Hydroxide ions can affect the properties and reactivity of Al(OH)3, making it less useful for certain applications. Additionally, in some cases, the presence of hydroxide may interfere with other reactions or processes.

5. Are there any risks associated with trying to remove hydroxide from Al(OH)3 with alkali metals?

Yes, attempting to remove hydroxide from Al(OH)3 with alkali metals can be dangerous due to the high reactivity of these metals. This reaction may also produce flammable or toxic byproducts, which can pose a risk to health and safety.

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